Expert Witness Profiler

Category: Statistics Expert Witness

  • Insurance Expert Allowed to Opine on Sales Tax Depreciation Practices

    Insurance Expert Allowed to Opine on Sales Tax Depreciation Practices

    Plaintiffs Melissa Pitkin and Dan Grout own a home together in Healdsburg, California. They hold a homeowner’s insurance policy from State Farm, policy number 57-C4-6752-1 (the “Policy”), which covered certain losses to their home and all of its contents. The Policy included the “main policy form” (FP-7955, CA) as well as a “homeowners endorsement form” (FE-3422). Subject to the Policy’s terms, conditions, and exclusions, the Policy included “Coverage B – Personal Property” limits of $506,574, and other various special limits. Regarding settlement of Coverage B claims, the Policy provides for settlement of damaged personal property in several ways, including actual cash value (“ACV”), market value, and replacement cost (“RC”).

    On August 20, 2020, the Walbridge Fire burned down the Plaintiffs’ home. Having lost their home and personal possessions, the Plaintiffs tendered a claim to State Farm for their losses under the Policy. State Farm accepted the claim and adjusted their losses pursuant to the Policy’s terms, which stated that the plaintiffs are entitled to recover ACV for their personal property losses. On December 16, 2022, and January 24, 2023, the Plaintiffs received partial payments from State Farm for their personal property contents losses. State Farm also sent the Plaintiffs “loss payment worksheets” that showed their ACV benefits for their personal property.

    For all items of property where sales tax was applicable, State Farm depreciated sales tax in calculating ACV.

    The Plaintiffs filed this class action, alleging that State Farm violates California law by depreciating sales tax as a component of RC when calculating ACV.

    State Farm sought to exclude the opinions of Plaintiffs’ experts, Greg J. Regan, David Melzer and Eugene Peterson while Plaintiffs filed a motion to exclude the testimony of State Farm’s primary expert witness, Dr. Duane L. Steffey.

    Accounting Expert Witness

    Greg Joseph Regan is a partner in the Forensic Consulting Services Group of Hemming Morse, LLC, and is a licensed CPA in California.

    Get the full story on challenges to Greg Regan’s expert opinions and testimony with an in-depth Challenge Study.

    Insurance Expert Witness

    David Melzer has worked in the insurance industry since 2011 in various specialist capacities. He worked for Travelers Insurance from 2013 to 2020, where he held positions including adjuster, technical specialist, and claims manager.

    After that, he started his own public adjusting firm, called Property Claims Consultant, Inc., where he handles first and third-party property claims, including personal property claims.

    He has held the position of President of Property Claims Consultant, Inc. since he started the firm in November 2020. He has “significant experience in processing and analyzing personal property insurance claims” and “experience working with industry-standard software used to process and track personal property claims, including Xactimate or XactContents.”

    Want to know more about the challenges David Melzer has faced? Get the full details with our Challenge Study report.

    Construction Expert Witness

    Eugene Peterson built his first home in 1974 – and has been a home builder, remodeler, and restoration contractor for over 35 years.
    He is a Past President of the Utah Home Builders Association and the Greater Salt Lake Home Builders Association. He is the CEO of Advise And Consult, Inc., an expert witness & consultant for restoration, personal property & construction related matters in the United States and Canada. Peterson has facilitated peer group meetings for Business Networks, Inc., and was an
    advisor, consultant & certified trainer for Xactware, Inc. (construction estimating software) for several years. He also actively performs insurance appraisals as an umpire or appraiser.

    Discover more cases with Eugene Peterson as an expert witness by ordering his comprehensive Expert Witness Profile report.

    Statistics Expert Witness

    Dr. Duane Leon Steffey holds a Bachelor of Science in history and mathematics, a masters in statistics, and a Ph.D. in statistics from Carnegie Mellon University. He has served as a consulting statistician for over thirty years, with a “breadth of applications in engineering, health, environmental science, and civil justice.”

    He is an elected Fellow of the American Statistical Association since 2009, as well as an Elected Member of the International Statistical Institute since 2015.

    Gain a comprehensive understanding of Duane Steffey’s qualifications and casework history with his Expert Witness Profile report.

    Discussion by the Court

    1. Greg Regan

    Regan indicated that he was “asked to provide a methodology to calculate available classwide damages.” State Farm produced an Excel file known as the “Combined Pitkin Dataset.”

    If a claim “involves more than a few items or is not settled during a first contact” the claims personnel may “utilize the XactContents® tool to assist in valuing lost property for claim settlement purposes.” Third party entity Verisk owns the XactContents® tool.

    To create the Combined Pitkin Dataset for this litigation, third-party Verisk first created a report containing data regarding personal property claims during the class period with an XactContents® actual cash value estimate.

    Regan clarified that while his “methodology to calculate damages” was laid out in his initial report, the supplemental report was meant to apply the methodology to the Combined Pitkin Dataset. Regan then proposed two alternative “scenarios” for calculating damages. Under the first scenario, damages would equal the amount of Sales Tax Depreciation applied to a claim, capped by any RC benefits available under the policy. Under the second scenario, Regan allocated Sales Tax Depreciation proportionally by comparing the claimant’s remaining RC benefits to the total recoverable depreciation and then applying that percentage to the amount of Sales Tax Depreciation.

    The crux of State Farm’s motion to exclude concerns the reliability of Regan’s opinions. Specifically, State Farm claimed Regan’s opinion hinges on (1) unreliable data, (2) unreliable identification of class members, and (3) incompatible and unreliable damages “scenarios.”

    a. Reliability

    State Farm first argued that Regan’s reliance on the Combined Pitkin Dataset lacked the “foundation” necessary to survive a Daubert motion.

    State Farm’s challenge is best understood as an attack on the assumptions underlying Regan’s analysis—mainly, that XactContents® is an accurate tool for measuring damages in this case.

    Regan indicated that he relied on State Farm’s own records, testimony from State Farm employees, “validation exercises,” “extensive testing,” and “adopting the more conservative input for purposes of measuring damages” when a disagreement in the data arose.

    The Court concluded that Regan has established by a preponderance of the evidence that his opinion is reliable and admissible, subject to cross-examination and presentation of contrary expert testimony.

    According to State Farm, Regan’s “three new groupings of purported class members (not reflected in the class definition or his prior opinions) produce unreliable and patently incorrect results.”

    However, Regan “organized his damage calculations in three groups to reflect the different circumstances of those groups.” While each group may present different factual circumstances, Regan “applied the same methodology to calculate damages across all groups.”

    State Farm finally challenged Regan’s two damages scenarios as unreliable and invalid. Regan sufficiently explained in his Report and Supplemental Report the reason for having two damages “scenarios,” how he reached those scenarios, and the methodological basis for each.

    b.  Untimely Opinions

    State Farm argued in the alternative that Regan’s opinions in the Supplemental Report should be excluded as untimely and improper new opinions.

    Regan’s Supplemental Report was disclosed two months after the Rule 26 disclosure deadline and less than one month before the rebuttal deadline. Because its own expert, Steffey, opined that the Supplemental Report “substantially revised Regan’s opinions,” State Farm urged that the Court find his “new” opinions as untimely under Rule 702. Plaintiffs responded by pointing out that the parties jointly agreed to extend fact discovery and adjust the pretrial schedule to allow for State Farm to produce the Combined Pitkin Dataset. As a result, Regan produced his Supplemental Report on September 25, 2025—a date agreed upon by the parties in their joint request to adjust the pretrial schedule.

    2. David Melzer

    a. Methodology

    Melzer indicated that he was “hired to provide opinions on . . . the frequency of personal property claims with State Farm, the ascertainability of these claims through available databases, and whether the claims of Plaintiffs Pitkin and Grout fall within the proposed class.”

    Melzer’s proposed methodology to estimate the total number of potential class members is as follows. To estimate the total volume of personal property replacement claims for State Farm in California from 2015 to the present, he analyzed the number of claims in a submarket: San Diego. He chose San Diego as a representative example because claims throughout California would “typically be consistent with personal property claims made in San Diego.”

    Using that data, Melzer estimated the total number of insurance claims in San Diego across all insurers by dividing the number of Travelers’ claims by its 3.68% market share (a percentage market share that is available on the California Property and Casualty Market Share Report published by the California Department of Insurance).

    He then consulted the California Property and Casualty Market Share Report (the “Market Report”) issued by the California Department of Insurance from 2015-2023 and determined that State Farm consistently has “over 8.5% of the Property and Casualty Insurance Market in California.”

    Melzer goes on to explain that based on his familiarity with Xactimate and XactContents®, he believes that “given the detailed data that insurance companies maintain and given the flexibility and power of Xactimate/XactContents, it is [his] opinion that State Farm can create a report, or export the necessary data, that will allow for the identification of all personal property insurance claims where State Farm depreciated the taxes. From that report, Plaintiffs will be able to identify the members of the Class.”

    b. Class Member Identification

    State Farm maintained that the Court must exclude any class identification opinion from Melzer, as he “has not purported to identify class members” and instead “conjectures that someone else can.”

    It similarly urged that Melzer’s “conjecture that someone else can reliably and feasibly identify specific class members based solely on the Combined Pitkin Dataset also lacks sufficient foundation, conflicts with Melzer’s other admissions, and is therefore inadmissible.”

    Plaintiffs contended that Melzer did, in fact, “analyze the capabilities of the Combined Pitkin Dataset to ascertain the members of the class.”They highlighted that Melzer provided a “detailed analysis of the capabilities of XactWare products, including XactContents.”

    “While State Farm may disagree” with this analysis, Plaintiffs concluded, “that is not a basis for the Court to exclude Melzer’s conclusions based on his extensive experience.” The Court agreed.

    c. Depreciation Standard Industry Practices

    State Farm similarly sought to exclude Melzer’s opinions on “sales tax depreciation practices for the insurance industry as a whole.”

    Plaintiffs responded by highlighting Melzer’s “more than a decade of experience regarding the adjustment of insurance claims,” including working for Farmers, Travelers, and during his “nearly five years as a public adjuster working with multiple insurers from 2020 to the present.”

    Much of that time was spent working with XactWare products, including XactContents®, which Plaintiffs believe render him qualified to “offer opinions as to the industry standard for adjustment of contents insurance claims.”

    As with his other opinions, the Court found that it is more likely than not that Melzer meets the four requirements. While a fact finder may conclude that State Farm’s sales tax depreciation practices are not what Melzer claims them to be, that does not render his opinion and testimony inadmissible.

    d. Rule 26 Testimony

    Plaintiffs acknowledged that “they, and State Farm, are precluded from offering undisclosed expert opinions.” But they maintained that “Melzer’s opinions as to the typicality of insurers not depreciating sales tax were explicitly disclosed in his report.”

    No party may offer undisclosed expert opinions at trial. The Court held that the example in the preceding paragraph was disclosed and will not be excluded.

    3. Eugene Peterson

    a. Methodology

    Peterson concluded that “XactContents® software contains global and line-item settings that allow an insurance company to apply depreciation based on one of three methods: 1) percentage, 2) by a fixed dollar amount, and 3) by age with an adjusted condition.” He opined, “the software allows complete control over how depreciation is calculated, so each insurance company can set its policies for depreciation without needing to customize the software. From the software’s perspective, a user can determine what line items are to be depreciated and what is to be depreciated in each line item, e.g., sales tax.”

    b. Opinions on XactContents® Data Extraction

    State Farm “did not dispute Peterson’s ability to testify regarding what the XactContents® tool is and how it may be used.” Instead, it sought to exclude Peterson’s “feasibility opinion—that the Combined Pitkin Dataset in this matter can be used by someone else to reliably identify class members or calculate damages.”

    The Court found that Peterson sought to offer a relatively narrow opinion with respect to the structure and abilities of XactContents® to assist Plaintiffs in calculating damages in this case. He has significant experience working with XactContents®. 

    4. Duane Steffey

    Steffey was hired by State Farm to “evaluate the basis and foundation for Regan’s, Melzer’s, and Peterson’s opinions” at class certification. State Farm also disclosed Steffey as a rebuttal expert to Regan’s supplemental report.

    a. Class Membership

    Plaintiffs took issue with how Steffey criticized Regan’s identification of 41,153 class members in his Supplemental Report.

    State Farm countered that Steffey’s rebuttal report criticizing Regan’s “new approach to identifying class members and calculating damages” was “based on his knowledge and education in statistics, previous experience, and the materials he reviewed.”

    The Court agreed with State Farm that exclusion is not warranted. Steffey engaged in a thorough review of the materials provided to him, including all exemplar claims identified by Regan. He then identified at least one “exemplar” Plaintiff who potentially lacked injury and damages, thus raising questions about Regan’s methodology for identifying class members.

    b. Damages Calculations

    Plaintiffs also sought to exclude Steffey’s criticism that Regan’s damages “scenarios” are “unreliable.”

    The Court found that Steffey raised important questions about Regan’s methodology that go to the heart of this dispute—questions regarding standing, injury, and how to identify class membership. His opinions are relevant. They can be tested. And they may assist the trier of fact in resolving the question of damages and standing in this case.

    c. Data Fields Interpretation

    Plaintiffs sought to exclude Steffey’s claim that some of Regan’s “descriptions of certain data fields in the Combined Pitkin Dataset ‘have not been corroborated by anyone with requisite knowledge.’”

    The Court found that Steffey properly critiqued Regan’s assumptions in the Combined Pitkin Dataset, a topic which he, as a statistician, may opine. That Steffey recognized he cannot judge the accuracy of the fields is a different question than identifying Regan’s failure to corroborate the Dataset. 

    d. Substantial Revision Opinion

    Plaintiffs finally sought to exclude Steffey’s opinion that Regan’s supplemental report represents a “substantial revision” to his analysis in the original report.

    Credibility is always an issue for the jury to consider, and Steffey’s opinion about the “drastic” change “underscores the unreliability of Regan’s approach generally.”

    State Farm is entitled to present this opinion as an attack on Regan’s credibility at trial. In sum, the Court will not exclude Steffey’s testimony.

    Held

    The Court denied the parties’ motions to exclude, as each request raises issues of credibility—a question reserved for the factfinder—instead of admissibility.

    Key Takeaway

     Plaintiffs must show it is more likely than not that: “(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert [has reliably applied] the principles and methods to the facts of the case.” Applying this standard, State Farm argues that Plaintiffs have not met their evidentiary burden.

    Case Details:

    Case Caption: Pitkin V. State Farm General Insurance Company
    Docket Number: 3:23cv924
    Court Name: United States District Court, California Northern
    Order Date: June 30, 2026
  • Statistics Expert Allowed to Opine on Over-Detention

    Statistics Expert Allowed to Opine on Over-Detention

    Plaintiffs Alanna Dunn, Reginald Haymon, Adam Day, Eric Zeider, Cameron Leonard, and Jason Wilson filed this class action alleging that the deliberate indifference of Cuyahoga County and the Cuyahoga County Sheriff’s Department caused them to be over-detained in the Cuyahoga County Jail after the legal basis for their detention ceased to exist.

    Plaintiffs retained Lacey Keller, a data scientist, as an expert witness to review and standardize files produced by the County relating to releases occurring between February 23, 2021 and December 31, 2023 while the County retained Dr. Sean Malone, a consultant who primarily works in statistics, finance, and economics, to rebut Keller’s analyses.

    The County sought to preclude Keller’s report while Plaintiffs sought to preclude Malone’s report.

    Data Science Expert Witness

    Lacey R. Keller is a seasoned data scientist with over 15 years of experience applying data to litigation, law enforcement, and investigations.

    She has been deposed nearly 30 times and has testified in over a half-dozen trials. She also joined the Washburn University faculty in 2025.

    Want to know more about the challenges Lacey Keller has faced? Get the full details with our Challenge Study report.

    Statistics Expert Witness

    Sean T. Malone is a consultant who primarily works in statistics, finance, and economics. He teaches finance and statistics at Trinity University.

    Discover more cases with Sean Malone as an expert witness by ordering his comprehensive Expert Witness Profile report.

    Discussion by the Court

    Lacey Keller

    Plaintiffs’ counsel asked Keller to conduct a variety of analyses, including calculating the time it took the County to release individuals after a triggering action, among other analyses on the timing of certain events relating to releases.

    For detainees with release-triggering event and no holds on their release, Keller found most were released in under 6 hours, and 95% were released in under 10 hours.

    In most cases, Keller found a booking hold added an additional 90 minutes to the release time. Once a booking hold was removed, the release usually occurred within the hour.

    Analysis

    The County argued that Keller’s report is unreliable and cannot be used to either (a) show the average time it took to release a detainee; or (b) ascertain whether a person is a member of the proposed class because the detainee’s time to release was greater than 12 hours.

    For the relevant time period, Keller identified 58,091 unique custody sessions. From there, Keller applied a series of exclusions to the data.

    The County argued that Keller’s methodology and opinions are unreliable because they solely rely on limited data not suited for determining release times.

    The County also faulted Keller’s report for not determining whether the data provided by Plaintiffs’ counsel could be used to determine actual time to release.

    First, information counsel provided to an expert does not render the opinions on which the expert relies insufficient. Second, there is a reasonable factual basis for Keller’s opinions. The report explained the sources from which the data came. It explained the exclusions applied to the custody sessions to obtain a sub-dataset that contains only custody sessions where there is an available release triggering event and subsequent release (among other information).

    Keller then explained how she conducted each calculation to arrive at her stated averages and conclusions. While the County vigorously challenges whether the underlying data can be used to calculate release times, those criticisms challenge the ultimate conclusions and not the reliability of Keller’s methodology or analysis.

    Whether the calculations are correct, accurate, or credible, is a separate question. As a result, the Court found that Keller’s methodology was reliable.

    Sean Malone

    Malone’s main conclusions are: Keller’s methodology for calculating time to release is unreliable because it is based on insufficient data and incomplete methods; Keller’s opinion is based on insufficient facts because it does not consider the individualized facts affecting time to release; Keller wrongfully groups together detainees leading to inaccurate time calculations; and Keller inappropriately excluded detainees which creates inaccurate time calculations.

    Analysis

    Plaintiffs argued that Malone is not qualified to opine on how to calculate over-detention of detainees because he is not an expert in release policies.

    Plaintiffs added that Malone’s expert opinions amount to “nothing more than legal conclusions about what facts are relevant and necessary” to an over-detention analysis.

    Lastly, Plaintiffs contended that Malone’s report is not the product of any reliable principles or methods.

    Malone’s experience in statistics plainly relates to his criticisms of Keller’s methodology for collecting data. It is appropriate for an expert in statistical analysis to criticize statistics prepared by another expert witness. And while Plaintiffs argued that Keller’s analysis is merely an “objective” calculation of the “time to release,” Malone’s report properly offered criticism of Keller’s underlying data, including her selection and purported manipulation of data. Malone’s criticism of the “limited” dataset Keller used to develop averages for “time to release” is appropriate rebuttal testimony.

    Because Malone is qualified to criticize the statistical analysis performed by Keller, and because his report properly challenges the data and methods used by Keller, the Court refused to exclude his report.

    Held

    • The Court denied the County’s motion in limine to preclude Lacey Keller’s expert report.
    • The Court denied the Plaintiffs’ motion to strike the expert report of Dr. Sean Malone.

    Key Takeaway

    Malone’s criticism of the dataset Keller used and the methods she used to calculate her “time to release” analysis is proper expert rebuttal.

    Case Details:

    Case Caption: Dunn V. Cuyahoga County
    Docket Number: 1:23cv364
    Court Name: United States District Court, Ohio Northern
    Order Date: March 31, 2026
  • Human Resources Expert Was Not Allowed to Opine on Overtime Exemption Status

    Human Resources Expert Was Not Allowed to Opine on Overtime Exemption Status

    Plaintiffs are current and former AutoZone employees, all of whom held roles as Store Managers between the years 2019 and 2022 and worked under district managers who oversaw operations in Montana.

    Due to AutoZone’s demographic structure, the collective currently includes Plaintiffs that work in AutoZone stores outside of Montana. Plaintiffs alleged that AutoZone willfully misclassified them as overtime-exempt, denying them overtime compensation for hours of work in excess of forty hours per week, in violation of the Fair Labor Standards Act.

    Defendants moved to exclude Plaintiffs’ experts Dr. Liesl M. Fox and Ramona Powell.

    Statistics Expert Witness

    Liesl Mae Fox has been a statistical consultant for over twenty-five years, including conducting analyses in the fields of litigation and medical research, and has testified as an expert witness.

    Want to know more about the challenges Liesl Fox has faced? Get the full details with our Challenge Study report.

    Human Resources Expert Witness

    Ramona Powell is a nationally certified Senior Professional in Human Resources. With a proven track record as an expert witness, Powell provided professional opinions and testimony in a wide range of employment-related matters.

    Get the full story on challenges to Ramona Powell’s expert opinions and testimony with an in-depth Challenge Study.

    Discussion by the Court

    A. Defendants’ motion to exclude expert Dr. Liesl Fox 

    Defendants sought to exclude Plaintiffs’ expert, Dr. Liesl Fox, from serving as an expert witness in this case. It appeared that Fox relied on data provided by Plaintiffs’ counsel to determine the average hours worked by each Plaintiff. According to Defendants, this data conflicts with the testimony of the individual Plaintiffs, rendering Fox’s opinions unreliable.

    The Court was inclined to grant Defendants’ motion to exclude the testimony of expert Dr. Liesl Fox. The calculations of the remaining Plaintiffs’ average hours worked “constitute basic math that a jury can compute without the opinion of an expert.” Notwithstanding the foregoing, the Court reserves ruling on the motion at this time.

    B. Defendants’ motion to exclude expert Ramona Powell

    Next, Defendants requested that the Court exclude Ramona Powell pursuant to Rule 702 “because her report is unreliable, her testimony improperly invades the province of the jury by making legal conclusions, and allowing her testimony under such circumstances would confuse the jury and be unfairly prejudicial to AutoZone.” The Court reserves ruling on the motion at this time.

    However, to the extent Powell offered opinions on the ultimate issue in this case—whether Defendants properly classified Plaintiffs as exempt from FLSA’s overtime requirements—such opinions will be excluded. These opinions invaded the province of the Court and/or the jury.

    Held

    The Court reserved ruling on both motions to exclude the testimony of Dr. Liesl Fox and Ramona Powell.

    Key Takeaway

    The Court must determine whether the witness is qualified as an expert by knowledge, skill, experience, training, or education, and whether the opinion will help the trier of fact.

    Case Details:

    Case Caption: Richter V. Autozoners, LLC
    Docket Number: 9:22cv47
    Court Name: United States District Court, Montana
    Order Date: April 30, 2026
  • Statistics Expert Allowed to Opine on PFAS Exposure

    Statistics Expert Allowed to Opine on PFAS Exposure

    This case arises out of the contamination of surface waters and drinking water in Chattooga County, Georgia, with per- and polyfluoroalkyl substances known as “PFAS.”

    In essence, Plaintiff Earl Parris, Jr., alleged that the Defendants have contaminated his city’s water supply and thus his household water with PFAS. Parris is a resident of Summerville, Georgia, who receives running, potable water to his home from the Summerville Public Works and Utilities Department.

    The City of Summerville—which has intervened in this case—used Raccoon Creek, a tributary of the Chattooga River, as the main source of its municipal water supply. The Defendants are the following companies, which allegedly manufactured and supplied the PFAS discharged into Raccoon Creek: 3M Company (“3M”), Daikin America, Inc., E.I. du Pont de Nemours and Company, and The Chemours Company. Parris alleged that Raccoon Creek and—consequently, his household water—have been contaminated with PFAS by the Defendants. PFAS can allegedly cause adverse health effects such as kidney and testicular cancer.

    Parris and Summerville have jointly moved to exclude the testimony of defense expert Laurentius Marais under Federal Rules of Evidence 702 and 403.

    Statistics Expert Witness

    Marthinus Laurentius Marais is a consultant specializing in applied mathematical and statistical analysis. He holds graduate degrees in mathematics, statistics and business administration from Stanford University. At the Stanford Graduate School of Business he received a PhD degree for a dissertation on applications of computer-intensive statistical methods to quantitative analyses of topics in business. He has served on the faculties of the University of Chicago and Stanford University.

    Discover more cases with Laurentius Marais as an expert witness by ordering his comprehensive Expert Witness Profile report.

    Discussion by the Court

    Marais’ expert report examined kidney and testicular cancer rates in counties with and without high PFAS levels in the water supply, including in Chattooga County, and concluded that there is “no statistically detectable, empirically significant indication of an association” between those cancer rates and PFAS exposure.

    A. Relevance

    The Plaintiffs contended that Marais’ conclusions regarding the lack of association between PFAS and cancer are irrelevant because this lawsuit is based on the city’s drinking water being out of compliance with the EPA’s PFAS limits, not based on personal injury damages from health costs.

    However, the Court agreed with the Defendants that Marais’ opinions are relevant.

    First, the Plaintiffs conceded that evidence regarding whether PFAS “can” cause cancer is relevant to this litigation, and Marais’s opinions may help a jury answer this question. Marais’ opinions compare cancer and PFAS statistics across counties in the United States, not just in Chattooga County.
    The Court is not persuaded by the Plaintiffs’ distinction between “general causation” evidence and “specific causation” evidence. That Marais’ opinions on PFAS and cancer included data from Chattooga County, where Summerville residents reside, is not grounds for excluding the opinions altogether.

    Second, the Plaintiffs’ extensive allegations of PFAS’ health risks are material to the relevance question. The Plaintiffs explicitly relied on such allegations in their claims for negligence (Counts V, VII), wanton conduct and punitive damages (Count VIII), and public nuisance (Count IX). Evidence that health risk never materialized is therefore relevant to the Defendants’ liability on those claims. For example, weighing testimony about the nonexistent association between PFAS and cancer in the Plaintiffs’ geographic area may help a jury evaluate whether the Defendants were negligent for manufacturing or failing to warn about PFAS in the first place.

    B. Reliability

    The Plaintiffs took issue with four aspects of Marais’ testimony: (1) it misinterpreted the underlying data, which Plaintiffs argue shows above-average testicular cancer rates despite below-average rates for all other types of cancer; (2) it compared county-level cancer data with city-level PFAS exposure data, which weakens the PFAS–cancer association in the case of Summerville because Chattooga County receives only about 20% of its drinking water from Summerville; (3) it is underinclusive because it did not account for latency effects, such as when a Summerville resident moves to a different county and develops cancer decades later; and (4) it is underinclusive because it did not include data from neighboring states where Summerville residents may have sought cancer treatment (e.g., at a Tennessee cancer center less than one hour’s drive away).

    Analysis

    The Court held that the methodology underlying Marais’ testimony was reliable. To begin with, any issues with the content of Marais’ conclusions in interpreting his own data are improper considerations at the admissibility stage. The focus of the reliability inquiry is on the expert’s “principles and methodology,” rather than his or her ultimate conclusions.

    Second, the county-city mismatch argument that the Plaintiffs identify is better suited for cross-examination than an admissibility challenge. The datasets on which Marais relies are produced by reputable organizations. The cancer data is produced at a county level from the National Center Institute, National Institute of Health, and Centers for Disease Control, and the PFAS data is produced at the public water district level by the EPA.

    Lastly, regarding the possibility that Marais’ dataset is underinclusive due to latency and residency problems, this argument too is more appropriate for cross-examination. Other than attempting to identify hypotheticals, the Plaintiffs have not pointed to any evidence that suggests Marais’ datasets depart from standard industry practice.

    For these reasons, the Court declined to exclude Marais’ testimony as unreliable. Marais has shown his methodology is sufficiently sound and that it is “properly grounded, well-reasoned, and not speculative.”

    C. Prejudice

    The Plaintiffs contended that Marais’ testimony will confuse the jury because it would question “(1) where his testimony fits into the City’s case, and (2) why the City has not offered any rebuttal evidence.”

    Any jury would understand the importance of introducing evidence on the health consequences of an alleged pollutant in a water pollution case, and the lack of rebuttal evidence is plainly not grounds for exclusion under Rule 403.

    Held

    The Court denied Plaintiff Earl Parris, Jr., and Intervenor-Plaintiff City of Summerville’s motion to exclude the testimony of Laurentius Marais. 

    Key Takeaway

    Datasets may be imperfect at times, but that is not grounds to render an entire analysis unreliable. The purpose of Daubert is to ensure that an expert “employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.”

    Please refer to the blogs previously published about this case:

    Polymers Expert Allowed to Opine on PFOS Sources

    Geology Expert’s Testimony on Potential Alternative Sources Admitted

    Case Details:

    Case Caption: Parris V. 3M Company
    Docket Number: 4:21cv40
    Court Name: United States District Court, Georgia Northern
    Order Date: March 13, 2026
  • Statistics Expert’s Scientific Analysis Excluded

    Statistics Expert’s Scientific Analysis Excluded

    This litigation arises from Plaintiff Raymond Flanks’ (“Plaintiff”) wrongful conviction for first-degree murder in 1985. Plaintiff alleged that the Orleans Parish District Attorney’s Office (“OPDA”) secured his wrongful conviction in violation of his constitutional rights by withholding material exculpatory evidence.

    Dr. Tumulesh Solanky is a statistician retained by Defendant Jason Williams to to conduct a scientific analysis of the alleged Brady violations and assess the reasonable conclusions that can be drawn regarding the frequency of such cases in Orleans Parish. Plaintiff filed a motion to exclude the testimony of Solanky.

    Plaintiff argued that Solanky’s proposed testimony should be excluded because: (1) the ratio of Brady violations to overall OPDA prosecution data is not an issue the jury will need to decide; (2) even if it were, a jury would not need expert opinion testimony to compare those numbers; (3) Solanky employed an unreliable methodology; (4) Solanky excluded certain cases, skewing the results; (5) Solanky has no data whatsoever to which he compares the numbers in New Orleans; and (6) his opinions are far outside the scope of his expertise as a statistician.

    Statistics Expert Witness

    Tumulesh K. Solanky is a professor and chair of the Departments of Mathematics and Physics at the University of New Orleans (UNO). He is a professor and chair of the Departments of Mathematics and Physics at the University of New Orleans (UNO). He has been teaching statistics and mathematics at UNO since August 1990.

    Get the full story on challenges to Tumulesh Solanky’s expert opinions and testimony with an in-depth Challenge Study.

    Discussion by the Court

    Solanky reviewed OPDA annual reports providing information about the numbers of cases screened, accepted, and tried over a period of 12 to 15 years. Solanky found that the average number of cases accepted for prosecution by OPDA annually was approximately 7,084. Extrapolating from the available data, Solanky found that between 1974 and 1985, there were approximately 522 trials and 5,175 guilty pleas on average each year. Thus, the total average number of combined trials and guilty pleas per year was approximately 5,698.

    The statistics provided by Solanky are not irrelevant. It is ultimately Plaintiff’s burden to “provide the context necessary to evaluate whether an alleged department-wide pattern is so obvious as to impart constructive notice.” Plaintiff intended to argue there was a sufficient number of Brady violations to put Connick on notice of a pattern, while Williams planned to argue there was not a sufficient pattern given the number of cases prosecuted by OPDA each year. Solanky used the linear regression model to extrapolate data for missing years.

    The jury can easily compare the total number of cases tried each year with the number of Brady violations to determine whether the “alleged department-wide pattern is so obvious as to impart constructive notice.” The jury does not need an expert to tell them that the percentages are not large. Solanky’s opinions that Brady violations were “exceptionally rare” or “exceedingly rare and very infrequent” are nothing more than argument. Allowing Solanky to testify to these issues would supplant the role of counsel in making argument at trial and the role of the jury in interpreting the evidence. The Court agreed with Plaintiff that a more appropriate denominator would be the number of cases with an appeal or post-conviction proceeding. Solanky’s report did not provide any data on that issue.

    Held

    The Court granted in part and denied in part Plaintiff’s motion to exclude the testimony of Dr. Tumulesh Solanky.

    Key Takeaway

    If the parties are unable to reach a stipulation on the average number of cases prosecuted and tried each year by OPDA, Solanky may testify to his use of the linear regression model to extrapolate this data. However, Solanky’s assertions that Brady violations were “exceptionally rare” will not assist the jury in understanding the evidence or determining a fact in issue.

    Please refer to the blog previously published about this case:

    Vocational Evaluation Expert Allowed to Opine on Lost Earning Capacity

    Legal Expert Was Barred From Opining on Good Time Credits

    Police Practices Expert’s Testimony on Eyewitness Identifications Admitted

    Case Details:

    Case Caption: Flanks V. City of New Orleans
    Docket Number: 2:23cv6897
    Court Name: United States District Court, Louisiana Eastern
    Order Date: December 30, 2025
  • Statistics Expert’s Testimony on Discriminatory Employment Decisions Limited

    Statistics Expert’s Testimony on Discriminatory Employment Decisions Limited

    The Plaintiffs had been employed by the Metropolitan Government of Nashville and Davidson County, Tennessee. They alleged in their lawsuits that, on May 4, 2020, they were either terminated or demoted for discriminatory reasons, and brought claims asserting many of the same legal violations.

    The Defendants filed two motions to exclude the testimony of Plaintiffs’ experts, Dr. Kenneth Smith and Dr. Robin Lovgren.

    Accounting Expert Witness

    Dr. Kenneth A. Smith has a PhD in Governmental Accounting and has worked as a Certified Public Accountant with local governments. Based on his published research and service on his local school board, he has specific expertise in public school district budgeting, accounting and financial management.

    Get the full story on challenges to Ken Smith’s expert opinions and testimony with an in-depth Challenge Study. 

    Statistics Expert Witness

    Dr. Robin Lovgren is an Associate Professor of Mathematics at Belmont University and has been teaching statistics for 16 years. She has overseen student statistical projects including a statistical regression analysis for the Human Resources Department of a local architectural and engineering firm recently.

    She earned her Master of Science in Statistics and Ph.D. in Management Science from the University of Tennessee in Knoxville.

    Want to know more about the challenges Robin Lovgren has faced? Get the full details with our Challenge Study report. 

    Discussion by the Court

    Kenneth Smith

    According to Kenneth Smith:

    1. “Elimination of the Central Office positions was discretionary and not mandated by the budget process”; and
    2. “The removal of these positions did not appear to follow the procedural and professional steps that commonly occur for budget-driven organizations.”

    Metro filed a motion to exclude Smith’s opinions on the basis that they were irrelevant and unreliable, and therefore inadmissible.

    Relevance

    Metro first argued that Smith’s opinion that the Central Office reorganization at Metro Nashville Public Schools (“MNPS”) was discretionary is irrelevant, because school budgeting always involves a certain amount of discretion, and Metro has never contended otherwise. Rather, Metro stated, it has always acknowledged that the fiscal year budget for fiscal year 2021 “reflected MNPS’ business judgment and budgetary discretion.” It argued that the jury will not be called upon to decide whether the Central Office reorganization was mandated by law but, instead, whether the employment decisions were retaliatory or discriminatory. “So,” it concluded, “an expert opinion that budgeting is discretionary and that reorganization was not required by law has no bearing on any fact of consequence in this case.”

    The Court disagreed. While there is no doubt that school budgetary decisions are largely discretionary, involving selections among many possible choices, Smith’s report suggested that Metro’s purported budgetary concerns were grossly overstated, given MNPS’ actual financial situation in 2020. The point of his opinion is that there were many other less controversial and more common areas within the budget from which Metro could have made up whatever deficit it believed it needed to cover, rather than taking the unusual step of cutting personnel first.

    Reliability

    Metro argued that Smith’s opinion that the Central Office reorganization did not “‘appear’ to follow the correct steps” is not reliable because it amounts to nothing more than speculation based on Smith’s “subjective notion about what should have or could have happened during [the] reorganization.”

    Smith observed that: (1) “budget pressure at MNPS in 2020 was fairly similar to prior years”; (2) “there were a large number of reasonable, routine & available options to address the budget pressure”; (3) “most budget options went through a substantive technical review process”; and (4) “this change [i.e., the elimination of Central Office positions] did not follow a substantive technical review process.”

    Therefore, Smith concluded that the removal of these positions did not appear to follow the procedural and professional steps that commonly occur for budget-driven reorganizations.

    The Court held that Smith’s opinion that the “Central Office Reorganization was not mandated nor necessitated by the budget process” is adequately supported and not based on mere speculation.

    Whether the Central Office Reorganization Resulted in Cost Savings

    Smith stated in his report that reorganizations like that undertaken by MNPS “sometimes result in actual cost savings, sometimes they are budget neutral and sometimes [they increase rather than decrease] the budget outflows.”

    Based on this statement, Metro argued that Smith cannot offer an opinion as to whether MNPS sought or achieved any particular cost savings through the Central Office reorganization.

    The Plaintiffs did not address this argument, and it did not appear that Smith offered or intended to offer any such opinion, as he expressly disclaims knowledge of whether cost savings were either projected or achieved. Accordingly, Metro’s request to exclude such an opinion is uncontested. The Court granted this small aspect of Metro’s motion.

    Robin Lovgren

    Robin Lovgren was asked by the Plaintiffs to “determine whether the employment decisions made in 2020 at [MNPS] show a pattern of discrimination based on engagement in protected activity.”

    She conducted a statistical analysis, based on information and documentation provided to her by the Plaintiffs that identified which employees were and were not known by Defendant Battle to have engaged in protected activity.

    Based on the information she reviewed, Lovgren concluded that “in 2020 a disproportionately large number of employees engaged in protected activities were adversely affected by the reorganization of the Central Office.”

    Statistical Analyses Based on the Number of Central Office Employees Who Had Engaged in Protected Activity

    Reliability

    Metro argued that Lovgren’s opinions are unreliable, because she failed to “support her opinions with sufficient facts or data to establish how many MNPS employees engaged in protected activity, or how many were adversely affected by the reorganization.”

    Lovgren’s opinion regarding which employees were and were not known to have engaged in protected activity was based on Defendant Dr. Adrienne Battle’s deposition testimony.

    The Court found it reasonable to assume that Battle, as Director of Schools for MNPS, understood the meaning of “protected activity” and knew what she was acknowledging when she stated she was not aware that any of the individuals had engaged in such activity. Moreover, it was undisputed that she knew the Plaintiffs had, in fact, engaged in protected activity. The Court concluded that Lovgren’s failure to define the term did not render her opinions unreliable.

    Likewise, as a matter of common knowledge, it was clear that being demoted, fired, or not rehired after a reorganization are “adverse” employment events, and Lovgren’s failure to define “adversely affected” as used in her report did not render her opinions unreliable.

    Relevance

    Metro argued that, because Lovgren’s opinions—based on the number of employees who were not known to have engaged in protected activity—were not reliable, they did not “tend to show that any facts are more or less probable” and therefore must be excluded for lack of relevance. However, because the Court found the opinions reliable, this argument failed.

    Statistical Analyses Based on the Number of Principals Who Had Engaged in Protected Activity

    Metro raised a separate argument regarding Lovgren’s analysis of the relative numbers of school principals who did or did not suffer an adverse employment action and who were or were not known to have engaged in protected activity. Lovgren conceded that she did not have any information regarding school principals (other than Plaintiff James Bailey) who were known to have engaged in protected activity.

    And in her explanation of the analyses regarding school principals, Lovgren stated: “The number of principals who engaged in protected activity was not known for this analysis so ‘what-if’ analyses were performed. The [analyses assume that] Bailey was the only principal who engaged in protected activity.”

    Because Lovgren admittedly cannot point to any facts in the record to support her assumption that Bailey was the only principal who was known to have engaged in protected activity, the Court held that her statistical analysis relating to school principals are not reliable and must be excluded.

    Held

    The Court granted in part and denied in part the Defendants’ motions to exclude the opinions of Dr. Kenneth Smith and Dr. Robin Lovgren.

    Key Takeaways:

    • An expert’s opinion, where based on assumed facts, must find some support for those assumptions in the record. Here, Lovgren’s opinion regarding which employees were and were not known to have engaged in protected activity was based on Defendant Battle’s deposition testimony.
    • Expert testimony should be supported by more than subjective belief and unsupported speculation and should be supported by good grounds, based on what is known. Smith’s opinion that the “Central Office Reorganization was not mandated nor necessitated by the budget process” is adequately supported and not based on mere speculation.

    Case Details:

    Case Caption: Hayes V. Metropolitan Government Consolidated Of Nashville and Davidson County, Tennesse
    Docket Number: 3:20cv1023
    Court Name: United States District Court, Tennessee Middle
    Order Date: July 10, 2025
  • Human Factors Expert’s Opinion on Driver Inattentiveness Excluded

    Human Factors Expert’s Opinion on Driver Inattentiveness Excluded

    This case arises out of an alleged design defect and failure to warn regarding a 2017 Toyota Tacoma. Lee Griffin was the primary driver of a 2017 Toyota Tacoma. After Griffin died due to accidental carbon monoxide poisoning from an automobile inadvertently continuing to run in the garage, Caroline Griffin filed suit individually and as executor of Lee Griffin’s estate.

    The Plaintiff filed a motion to exclude the entire testimony of Randall Tackett and Angela McGrath as well as part of the testimony of Nathan Dorris and Harry Pearce II.

    Toxicology Expert Witness

    Dr. Randall Tackett received his BS from Jacksonville University in 1975. He then received an MS degree in pharmacology and toxicology from Auburn University in 1977 and his Ph.D. in pharmacology and toxicology from the University of Georgia in 1979. Following a two-year postdoctoral fellowship at the Medical University of South Carolina, he returned to the University of Georgia as an assistant professor in the Department of Pharmacology and Toxicology.

    He later served as a Professor and Associate Department Head in the Department of Clinical and Administrative Pharmacy at the University of Georgia College of Pharmacy.

    Get the full story on challenges to Randall Tackett’s expert opinions and testimony with an in-depth Challenge Study. 

    Statistics Expert Witness

    Angela A. McGrath has a Bachelor of Science in Statistics, a Master of Arts in Applied Statistics, 27 years of experience in consulting, and experience teaching statistics.

    She is the Principal Consultant and Director of Automotive Research at Cirque Analytics, an economic, statistical, and financial consulting company headquartered in Jackson Hole, WY. She has developed extensive experience in formulating, conducting, and directing statistical and other quantitative analyses.

    Want to know more about the challenges Angela McGrath has faced? Get the full details with our Challenge Study report. 

    Automotive Engineering Expert Witness

    Harry Pearce has over 24 years of expertise in the field of structural crashworthiness. He gained industry experience with nine years at General Motors, serving as the Lead Structural Design Engineer for multiple vehicles. 

    With his knowledge and experience with vehicle sealing, Pearce has addressed claims of Carbon Monoxide (CO) intrusion. He has performed Electro Magnetic Interference (EMI) testing in anechoic chambers and Brake Override System (BOS) testing at Exponent’s Test and Engineering Center. 

    Discover more cases with Harry Pearce as an expert witness by ordering his comprehensive Expert Witness Profile report.

    Human Factors Expert Witness

    Nathan Todd Dorris is a human factors specialist with extensive experience in product safety and the evaluation of instructions, warnings and other safety communications for a broad range of products and industries.

    Gain a comprehensive understanding of Nathan Dorris’ qualifications and casework history with his Expert Witness Profile report.

    Discussion by the Court

    A. Randall Tackett

    Randall Tackett stated two opinions in his expert report:

    1. Griffin consuming 1.2 standard drinks within the hour before death is inconsistent with the evidence described above. Rather, the timeline of events is consistent with Lee Griffin ingesting higher amounts of alcohol earlier on July 4, 2022, which his body would have metabolized from the time he ingested the alcohol until his death.

    2. It is more likely than not that on the evening of July 4, 2022 Griffin’s blood alcohol concentration was at a level that could have affected his reaction time, hearing, judgment, memory, reasoning and ability to detect danger including his ability to turn off his Toyota Tacoma and/or recognize that it was still running in the garage.

    Motion to Exclude

    In this case, Tackett attempted to estimate the decedent’s blood alcohol content (BAC) at various times before death using a method known as retrograde extrapolation. The Plaintiff did not dispute the scientific validity of this technique in general. Instead, she argued that Tackett lacked the necessary factual basis to apply it reliably in this case.

    Specifically, the Plaintiff pointed out several critical unknowns: the exact time of death, the time the vehicle was parked, and any concrete details about when, what, or how much alcohol the decedent consumed. The Defendants contended that these gaps in information should affect how much weight the jury gives Tackett’s testimony, not whether it should be allowed at all. The Court disagreed.

    The main issue, according to the Court, was the absence of reliable timing data. Without knowing when key events occurred, it was unclear how far back Tackett should extrapolate. His estimates ranged from one to two hours before death to as far as 14–15 hours earlier. As a result, his BAC estimates varied widely—from 0.046 to 0.297—depending on assumptions about timing and the decedent’s metabolism rate. Notably, there was also no evidence that the decedent had consumed any alcohol before parking the car, further undermining the reliability of Tackett’s conclusions.

    Angela McGrath

    The Defendants have proffered Angela McGrath as an expert witness to testify about the following opinions:

    a. [The United States Consumer Product Safety Commission (“CPSC”)] death certificate data shows that vehicles with and without keyless ignition have inadvertently been left running in enclosed spaces.

    b. Available CPSC death certificate data does not show a consistently increasing trend of accidental carbon monoxide poisoning from passenger vehicle exhaust in enclosed spaces.

    c. The proportion of combustion engine vehicles on the road with keyless ignition is increasing over time, however, even by 2021, the majority of vehicles still have conventional keys.

    d. While number of registered vehicles with keyless ignition and without [automatic engine time-out (“ETO”)] has increased steeply since 2011, the rates of accidental carbon monoxide poisoning from passenger vehicle exhaust in enclosed spaces has exhibited no corresponding, consistently increasing trend.

    Motion to Exclude

    The Plaintiff argued that McGrath’s opinions were unreliable because the CPSC database she relied on did not distinguish between carbon monoxide poisoning deaths caused by vehicles with keyless ignition systems and those with traditional mechanical ignitions. As a result, the Plaintiff contended that no meaningful statistical analysis could be done to compare the risks associated with each type of ignition system.

    In response, the Defendants claimed the Plaintiff had misrepresented McGrath’s testimony. They asserted that McGrath was not attempting to directly compare the risks of carbon monoxide deaths between mechanical and keyless ignition systems. However, this argument fell short.

    The Court noted that McGrath’s analysis implicitly relied on such a comparison. Her underlying logic was that if keyless ignition systems were more dangerous, the overall number of accidental carbon monoxide deaths would have increased after their introduction. Because the death rate did not rise, she inferred there was no added risk. Therefore, despite the Defendants’ assertions, McGrath’s analysis did, in fact, depend on comparing the two types of ignition systems—making the Defendants’ denial unconvincing.

    Moreover, the Defendants’ argument rested on the assumption that, absent a defect, accidental carbon monoxide deaths would have remained constant from 2011-2021. The Court found this assumption questionable. Public awareness campaigns, increased usage of carbon monoxide detectors, or other safety measures could have contributed to a decline in deaths over time—independent of any defect. McGrath’s analysis failed to account for such alternative explanations.

    Ultimately, the Court held that McGrath’s testimony offered nothing more than a basic correlation and lacked consideration of other plausible factors. As such, her statistical analysis could not be reliably used to show the absence of a defect.

    Nathan Dorris

    The Plaintiff sought to exclude four categories of opinions that Dorris asserted: (1) that the Tacoma’s warnings were sufficient, (2) that drivers lose focus while using their vehicles, (3) that the Plaintiff and decedent should have had carbon monoxide detectors in their home, and (4) that the Tacoma was not defective because it complied with regulatory and voluntary standards.

    Inattentive Drivers

    The Plaintiff sought to exclude Dorris’ opinions regarding how driver inattentiveness could lead individuals to leave their engines running and fail to respond to alerts or other feedback.

    In response, the Defendants argued that “ Dorris’ discussion of driver distraction is just one component of the opinions he expresses in this case and is background to his primary opinions specific to the 2017 Toyota Tacoma’s Smart Key System and the subject incident.”

    The statements in question included: “ [d]rivers that are distracted or inattentive (for whatever reason) can inadvertently leave their vehicle’s engine running, regardless of the type of ignition system employed,” and “[n]ot only can inattention result in execution errors and omitted actions, but it may cause individuals not to respond to alerts or other feedback.”

    Dorris was not particularly clear about whether these statements—or others like them—were independent expert opinions or merely facts supporting other opinions. Even the Defendants appeared uncertain. On one hand, they described these statements as “ background to his primary opinions,” but on the other, they defended his ability to offer them as standalone opinions.

    While Dorris may not opine directly that a driver’s inattentiveness causes errors, the Court held that if that fact properly supported a valid expert opinion offered by Dorris, he was permitted to rely on it.

    Sufficiency of the Warning

    Dorris opined that the warning provided by Toyota are “reasonable and appropriate.” The Plaintiff asserted that that opinion is unhelpful because it does not offer any analysis outside of what the jury can do itself. 

    Whether a warning is legally sufficient depends upon the language used and the impression that such language is calculated to make upon the mind of the average user of the product. The Court held that the adequacy inquiry here takes the perspective of the user of the product. Therefore, the jury is fully capable of determining whether the adequacy of the warning(s) at issue here without the help of an expert.

    Carbon Monoxide Detectors

    The Plaintiff argued that “ Dorris attempted to opine that the Griffins should have equipped their home with carbon monoxide detectors.”

    However, the only relevant statement on the page of Dorris’s report cited by the Plaintiff read:

    “ In a publication dated 08/2020, the Georgia Department of Public Health explicitly discussed CO exposure can cause ‘sudden illness or death’; potential sources of CO exposure include automobile exhaust; to install CO detectors ‘in every room used for sleeping’; ‘DO NOT leave a motor vehicle running in an enclosed garage.“

    This statement appeared under the section titled “ Exhaust Fumes and CO Are Well Known Hazards.” Aside from the quoted portion referencing carbon monoxide detectors, there was no other mention of detectors—either in that section or anywhere else in the report.

    The Court did not view this as Dorris offering an opinion that the Plaintiff or the decedent should have installed carbon monoxide detectors in their home. Instead, the Court found that he was merely citing a source he relied upon to support his broader conclusion that “ Exhaust Fumes and CO Are Well Known Hazards.”

    Importantly, the Plaintiff did not challenge Dorris’s qualifications to reach that conclusion, nor did they argue that the conclusion itself was unhelpful.

    Compliance with Relevant Standards

    The Plaintiff moved to bar Dorris from testifying that the Toyota Tacoma was not defective simply because it complied with minimum regulatory standards.

    In response, the Defendants argued that the jury had a right to consider federal compliance when evaluating whether the vehicle’s design was reasonable. They further claimed that Dorris relied on compliance as just one of several factors in concluding the Tacoma was not defective. However, the Court sided with the Plaintiff.

    Dorris had stated that the lack of an automatic engine shutoff did not make the Tacoma defective, in part because ” at the time the subject vehicle was manufactured and sold (and even today), such a feature is not required by any regulation or voluntary standard.” In other words, he based his opinion on the fact that the Tacoma complied with federal regulations.

    The Court found this reasoning insufficient and ruled that it warranted exclusion. Accordingly, the Court held that Dorris would be precluded from opining that the Tacoma was in compliance with federal regulation.

    Harry Pearce II

    The Plaintiff sought to exclude four of his opinions from testimony: (1) opinions going to intent, motive, or state of mind, (2) opinions about the source of the carbon monoxide, (3) opinions about the efficacy of carbon monoxide detectors would have had in this case, (4) opinions “parroting” Jeya Padmanaban.

    Intent, Motive, and State of Mind

    The Plaintiff argued that Pearce should not be allowed to testify about Toyota’s subjective state of mind.

    On that point, the Plaintiff was correct—Pearce could not offer opinions about what the Defendants were thinking, such as “ Toyota did not want to [install auto shutoff] because of the concern of introducing a new risk of hot car deaths.” Such statements improperly speculate on Toyota’s intent or motivations.

    However, the Defendants were also partially correct. Pearce was permitted to rely on Toyota’s internal documents and employee testimony to form his expert opinions. He “ may testify as to whether information contained in Defendants’ internal documents indicated certain risks.” The Court clarified that while Pearce could interpret the content of internal materials to identify risk indicators, he could not speculate on Toyota’s actual intent or decision-making process.

    Source of Carbon Monoxide

    The Plaintiff moved to exclude any opinion from Pearce regarding the source of the carbon monoxide that caused her and the decedent’s injuries.

    When asked directly whether he had an opinion on the source of the carbon monoxide in this case, Pearce responded, “ I was not asked to do that so I do not have an opinion on that.“

    Despite this, the Defendants added a qualification. They stated that Pearce would not offer an opinion on the matter “ unless Plaintiff opens the door to this subject through her attorneys’ examination of Pearce or the testimony of other witnesses she presents at trial.“

    But as the Defendants were well aware, the Plaintiff had already retained an expert specifically to testify about the source of the carbon monoxide. And since causation is a central element of the Plaintiff’s claims, it was almost certain the Plaintiff would “open the door“ to this issue during trial.

    That, however, did not give the Defendants license to question Pearce on a subject about which he had explicitly disclaimed any opinion. If the Defendants wished to challenge the Plaintiff’s expert on the source of the carbon monoxide, they should have retained their own rebuttal expert.

    Carbon Monoxide Detectors

    Pearce intended to opine that, “[w]ith multiple sources of CO in a home, the best protection from CO exposure is the installation of CO detectors in the home. Auto engine shut-off only protects from the one vehicle on which it is installed.”

    The Plaintiff objected to this because it depended on two assumptions: (1) that any carbon monoxide detectors in the house would have worked and (2) that the Plaintiff and the decedent would have responded to the carbon monoxide detector if it did work. 

    However, the Court held that Pearce has extensive experience from which he could derive his opinion.

    Parroting

    The Plaintiff argued that any testimony by Pearce regarding a 2015 paper published by Jeya Padmanaban would be irrelevant and amount to inadmissible “parroting.”

    In response, the Defendants clarified that they did not intend to have Pearce testify about Padmanaban’s research. Instead, Pearce had included the study merely as general background material.

    The Defendants confirmed that they would not raise the Padmanaban study at trial unless the Plaintiff opened the door to that line of testimony. Based on this clarification, the Court denied this portion of the Plaintiff’s motion to exclude.

    Held

    • The Court granted the Plaintiff’s motion to exclude Randall Tackett’s testimony.
    • The Court granted the Plaintiff’s motion to exclude Angela McGrath’s testimony.
    • The Court granted in part and denied in part the Plaintiff’s motion to exclude Nathan Dorris’ testimony.
    • The Court granted in part and denied in part the Plaintiff’s motion to exclude Harry Pearce’s testimony.

    Key Takeaways:

    1. An expert’s testimony is not relevant and may be excluded if it is directed to an issue that is well within the common sense understanding of jurors and requires no expert testimony.
    1. Experts may not testify that a party was in compliance with a federal regulation. Whether someone has violated or is in compliance with the law is a legal conclusion.
    1. Expert testimony about a party’s intent, motive, or state of mind is inadmissible.

    Case Details:

    Case Caption: Griffin V. Toyota Motor Corporation Et Al
    Docket Number: 1:23cv3107
    Court Name: United States District Court, Georgia Northern
    Order Date: June 18, 2025
  • Statistics Expert Witness’ Damages Calculation Limited Because She Included Extended Gap Periods in Her Analysis

    Statistics Expert Witness’ Damages Calculation Limited Because She Included Extended Gap Periods in Her Analysis

    Defendant, New Prime, Inc., is a commercial trucking company, and its drivers are required to have a Commercial Driver’s License (“CDL”). It designates its CDL-licensed drivers as A seat, B seat, and C seat. B and C seat drivers are paired with an A seat driver until they attain enough experience to be an A seat driver and are paid less than A seat drivers.

    Separately, Defendant created a program whereby individuals could receive the training necessary to obtain a CDL. This program has been referred to as the Prime Student Driver program, or “PSD program,” and participants have been referred to as “PSDs.” PSDs earn a Commercial Learner’s Permit (“CLP”) as part of that training, and at least some of those with a CLP drive a truck carrying freight for Defendant. Such PSDs are designated “D seat drivers” and must be accompanied by an A seat driver. PSDs are not paid, even when performing duties as a D seat driver.

    Plaintiff, Peter Nyachira, asserted two claims. First, he alleged the failure to pay PSDs (or, perhaps, PSDs when acting as D seat drivers) violates the Fair Labor Standards Act (the “FLSA”) and Missouri’s Minimum Wage Law (the “MMWL”). Second, he asserted the amount paid to B and C seat drivers did not meet the FLSA’s minimum wage requirement.

    One of the factual issues to be resolved is how much time B and C seat drivers worked. This issue is also relevant for PSDs if it is determined they were “employees” under the FLSA and MMWL. Another issue that must be resolved is whether the amount paid to B and C seat drivers satisfied the minimum wage requirements. Plaintiff retained Liesl Fox to testify on these matters.

    Statistics Expert Witness

    Liesl M. Fox is a Senior Consultant and Partner at Quantitative Research Associates, a firm that provides statistical and computing consulting services, where she has been employed since 1997. She has been a statistical consultant for over twenty-five years, including conducting analyses in the fields of litigation and medical research, and has testified as an expert witness.

    Get the full story on challenges to Liesl M. Fox’s expert opinions and testimony with an in-depth Challenge Study. 

    Discussion by the Court

    Basis for Estimates

    Fox’s estimates of the amount of time B and C seat drivers were working were called into question. To place the issue in context: drivers recorded their time in categories pursuant to the Department of Transportation’s Hours of Service (“HOS”) regulations.

    The Court has already held in one of its previous rulings that the HOS categories did not correspond to time “worked” by drivers, and they therefore could not be relied on for that purpose. The Court further concluded drivers are working regardless of the HOS code that is entered and “this means that drivers engaged in multi-day trips are working 24 hours a day.”

    Defendant argued Fox’s estimates did not sufficiently rely on the HOS logs. However, given the Court’s ruling, there is no basis for concluding Fox’s opinion should be excluded because she did not rely on the HOS logs more than she did.

    Allocation of Time

    Defendant retained its own expert, Dr. Christopher Stanton, Ph.D, to rebut Fox’s opinions and relied on his opinion to fault Fox for “assigning all time corresponding to the full duration of a trip that spans two weekly pay periods to the weekly pay period when the trip ended.”

    It claimed this approach artificially inflates the number of hours worked in the second of the two weeks, creating a false impression that insufficient wages were paid for that week.

    Plaintiff defended Fox’s approach by contending, essentially, that (1) Defendant’s records did not permit a different calculation method that is superior to the one she employed and (2) there is no artificial inflation of damages because Defendant pays drivers a set base amount each week.

    The Court concluded that the dispute between Stanton and Fox did not affect the admissibility of Fox’s opinion. Defendant was free to cross-examine her on the issue, as well as present Stanton’s alternative calculation for the jury’s consideration.

    Starting Point for Calculations

    A collective action was certified under the FLSA for those claims, and a class was certified under Federal Rule of Civil Procedure 23 for the PSDs to assert an Missouri’s Minimum Wage Law claim.

    The class definition for the collective action includes B, C, and D seat drivers who engaged in over-the-road training or team driving since May 9, 2020. The starting point for the Rule 23 class is also May 9, 2020. However, Fox calculated damages for the FLSA claims and the MMWL claims beginning on April 13, 2020, and May 3, 2020, respectively. Plaintiff defended this approach for the FLSA claims by arguing that if Defendant’s violation of the FLSA is willful, the statute of limitations is three years. He provides no explanation for the MMWL claim.

    Defendant insists that the measure of damages is confined to the period described in the class definition. Neither party discusses the issue sufficiently to permit the Court to rule, so the Court defers ruling. Evidence of damages from before May 9, 2020, will not be permitted until the matter is resolved.

    “Blank” Codes for D Seat Drivers

    In addition to requiring drivers to record HOS time entries, Defendant maintained a calendaring system. Drivers are assigned various codes; for instance, “D” indicates they are under dispatch, and “A” indicates they are available for dispatch. In some instances, the calendaring system contains gaps; that is, there is not a code for every moment of every day. Fox defined an “Extended Gap Period” as one lasting 24 hours or more.

    For B and C seat drivers, Fox compared the time covered by Extended Gap Periods to Defendant’s Duty Status Records; if the Duty Status Records indicated the B or C seat driver was working, Fox counted the Extended Gap Period as time for which compensation was due.

    Fox treated PSDs differently. She compared the Extended Gap Period to the Duty Status record; then, if the Extended Gap Period ‘was associated with a calendar code . . . or had no calendar code, the gap remained in the analyses.’ Thus, even when confirming information was absent, Fox’s calculations assumed PSDs were working, despite neither the calendaring system nor the Duty Status records reflecting this. The Defendant argued there is no basis in the record for this assumption.

    The Record establishes the calendaring system was not used for PSDs. Moreover, in her deposition, Fox conceded that 99% of the PSDs did not have any calendar codes, but she included the Extended Gap Periods because doing so is consistent with Plaintiff’s theory.

    PSDs were entitled to compensation for the Extended Gap Periods

    Plaintiff did not explain why PSDs were entitled to compensation for the Extended Gap Periods when (1) no available records suggested they were working during that time and (2) Extended Gap Periods were reflected in a calendaring system that is not used for PSDs. The Court concluded Fox had no basis for including Extended Gap Periods in the number of hours PSDs potentially worked, and therefore this component of her analysis must be excluded.

    Orientation Time for Certain B and C Seat Drivers

    Finally, Defendant argued orientation time for certain B and C seat drivers should be excluded. The Court need not consider Defendant’s argument because the Court granted Defendant summary judgment on Plaintiff’s claim regarding orientation. In other words, damage calculations for this aspect of Plaintiff’s claim were irrelevant and will not be admitted at trial.

    Held

    The Court granted in part, denied in part and deferred in part the Defendant’ motion to strike the expert testimony of Dr. Liesl Fox.

    The Court excluded Fox’s opinions regarding (1) Extended Gap Time for D seat drivers and (2) damages incurred by B and C seat drivers related to their attendance at orientation.

    Key Takeaway:

    Based on Stanton’s alternative calculation, the Defendants claimed that Fox’s approach artificially inflates the number of hours worked in the second of the two weeks, creating a false impression that insufficient wages were paid for that week. However, the dispute between Stanton and Fox did not affect the admissibility of Fox’s opinion.

    Fox conceded that 99% of the PSDs did not have any calendar codes, but she included the Extended Gap Periods because doing so is consistent with Plaintiff’s theory. The Court concluded Fox had no basis for including Extended Gap Periods in the number of hours PSDs potentially worked, and therefore this component of her analysis must be excluded.

    Case Details:

    Case Caption: Nyachira V. New Prime, Inc.
    Docket Number: 6:21cv3211
    Court: United States District Court, Missouri Western
    Order Date: September 13, 2024
  • Statistics Expert Witness’ Potential Backpay Calculation Excluded

    Statistics Expert Witness’ Potential Backpay Calculation Excluded

    Named Plaintiffs Mary Alice Clark, Christopher Coulter, Aaron Perez, Kevin Nelson and Phillip Roscher (collectively, “Plaintiffs”), individually and on behalf of all others similarly situated, brought this putative collective action against Defendant Capital Vision Services, LLC d/b/a MyEyeDr (“MyEyeDr” or the “Company”), claiming that MyEyeDr misclassified all General Managers (“GMs”) and General Managers-in-Training (“GMITs”) as exempt from the overtime pay requirements imposed by the federal Fair Labor Standards Act (“FLSA”), as well as Massachusetts and Pennsylvania law.

    MyEyeDr filed a motion to exclude Plaintiffs’ proffered expert witness, Dr. Liesl M. Fox under Fed. R. Evid. 702 and 403.

    Statistics Expert Witness

    Liesl M. Fox, Ph.D. is a Senior Consultant and Partner at Quantitative Research Associates, a firm that provides statistical and computing consulting services. She has been a statistical consultant for over twenty-five years, including conducting analyses in the fields of litigation and medical research, and has testified as an expert witness.

    Furthermore, she has consulted on and testified in numerous matters involving wage-and-hour disputes, including claims under the Fair Labor Standards Act of 1938 (“FLSA”). These matters have involved allegations of unpaid overtime, off-the-clock work, employment misclassification, minimum wage violations, time-shaving, record-keeping violations, and other wage-and-hour issues.

    Get the full story on challenges to Liesl Fox’s expert opinions and testimony with an in-depth Challenge Study. 

    Discussion by the Court

    Reliability

    Initially, MyEyeDr challenged Fox’s opinions on several grounds. As to the calculation of potential backpay, she assumed that all of the GMs’ training last eight weeks when there was testimony from MyEyeDr’s Chief Revenue Cycle Officer that such period could be shortened, and two class members for which she had made such calculation, testified that neither undertook such training and others testified to a shorter training period.

    Consequently, the Court held that the fact that Fox’s calculation for backpay were premised on such unsupported assumptions undermined the reliability of those calculations. Similarly, in her opinion regarding whether Plaintiffs supervised the equivalent of two full-time employees (for the purposes of determining if the executive exemption applied), the Court found that she did not account for inventory hours spent by these employees “which artificially deflated the labor hours GMs supervised.”

    Moreover, according to the Court, the key is that there is no explanation of a reliable methodology in which she included some work hours in her analysis and excluded others.

    Helpfulness to the Trier of Fact

    Next, the Court questioned whether Fox’s opinions will be helpful to the trier of fact.

    If MyEyeDr is found to have violated the FLSA, it would owe backpay for uncompensated overtime hours worked by GMs at a rate of one and a half times their hourly rate. Upon determining the number of overtime hours each GM worked, the jury would be tasked with calculating each individual’s hourly rate by dividing the weekly salary by the number of hours worked that week. To calculate the backpay, the jury would (1) multiply the hourly rate by one and a half and (2) multiply that by the GM’s overtime hours that given week. Such calculations constituted basic math that a jury can compute without the opinion of an expert.

    However, Plaintiffs noted that the payroll data in this case “contains more than 95,400 rows of data” spanning five years with “81 different earnings code[s] some of which are included in the damage calculations and others that are not properly included in the regular rate,” and “it contains unpaid and paid time off hours that need to be excluded from hours work estimates, and . . . bonuses that need to be spread over the time periods during which they are earned.” They argued that, given the enormity of the data, a jury is unlikely to have the ability to do these calculations. 

    Nevertheless, the Court held that such data can be presented in summary fashion to the jury. Plaintiffs may explain the meaning of such numbers through lay witnesses and argue the reasonable inferences that can be drawn from same to the jury. The Court decided that this proffered “opinion” did not require specialized knowledge or would be helpful to the jury as required under Fed. R. Civ. P. 702.

    Risk of Undue Prejudice and Confusion to the Jury

    Furthermore, the Court held that there is a risk that the jury will attach undue significance to this opinion offered by Fox based on the deficiencies addressed above, such that any probative value of same is outweighed by the risk of undue prejudice and confusion to the jury under Rule 403.

    Held

    In conclusion, the Court granted the Defendants’ motion to exclude Plaintiffs’ proffered expert witness, Liesl M. Fox.

    Key Takeaways:

    To begin with, MyEyeDr did not challenge Fox’s credentials as a highly qualified statistical consultant, or the general relevance of her proffered opinions, but challenged their reliability on several grounds and posited that her proposed testimony would be unhelpful to the jury.

    • First of all, Fox’s testimony would not assist the jury because Fox’s calculations are basic math that a jury can compute without the opinion of an expert.
    • Secondly, Fox’s calculation for backpay were premised on unsupported assumptions. For instance, Fox assumed that all of the GMs’ training lasted eight weeks when there was testimony from MyEyeDr’s Chief Revenue Cycle Officer that such period could be shortened.

    Case Details:

    Case Caption: Clark Et Al V. Capital Vision Services, Llc
    Docket Number: 1:22cv10236
    Court: United States District Court for the District of Massachusetts
    Order Date: July 18, 2024
  • Court validates the objective findings of the statistics expert witness in this class action lawsuit consisting of disability discrimination claims

    Court validates the objective findings of the statistics expert witness in this class action lawsuit consisting of disability discrimination claims

    This case originated from a class action lawsuit filed by the Center for Independence of the Disabled, New York and other nonprofit organizations (collectively referred to as Plaintiffs) against the Metropolitan Transportation Authority (“MTA), New York City Transit Authority (“NYC Transit”), and the City of New York(“the City”) (collectively referred to as Defendants). The lawsuit alleged that hundreds of thousands of New Yorkers with mobility disabilities were persistently and discriminatorily excluded from accessing the New York City subway system due to the failure of the Defendants to adequately maintain the already limited number of elevators in the system. 

    The Plaintiffs contended that subway riders with mobility disabilities routinely faced abrupt and extended elevator outages lasting for months, without any prior notice or warning mechanisms like signage or announcements. Moreover, the Defendants allegedly failed to provide any alternative accommodations to facilitate the transportation of people requiring elevator access when outages occurred. The Plaintiffs asserted that the overall elevator accessibility in the New York City subway system was already poor compared to other major US cities, with only 112 (24%) of the 472 subway service line stations in New York City being wheelchair-accessible.

    Public data from the MTA demonstrates that over 9,019 elevator outages occurred during the one-year period ending on June 30, 2015. Over 4,100 of those outages were unscheduled—a predictable result of Defendants’ failure to maintain and implement adequate preventative maintenance procedures

    Plaintiffs alleged that Defendants’ failure to maintain the limited number of elevators they provide in the New York City subway system violated federal and local disability rights laws, including Title II of the Americans with Disabilities Act (“ADA”), Section 504 of the Rehabilitation Act of 1973, and the New York City Human Rights Law (“NYCHRL”). The Court was left to assess whether Defendants have established that they provide reasonable accommodations to class members when elevator outages prevent them from accessing the subway.

    The Defendants retained Dr. Alan J. Salzberg, a statistician, to analyze the overall median availability of elevators in the NYC subway system using MTA data. The Plaintiffs did not contest his availability calculations but argued that the aggregated figures could obscure variability. Hence, the Plaintiffs presented two rebuttal experts – Andrew D. Schwarz and Sylvia Morse – to provide context to Dr. Salzberg’s opinions. 

    The Plaintiffs also filed a motion to exclude Dr. Salzberg’s testimony, arguing that he exceeded his expertise scope, manipulated data unreliably, and made flawed assumptions, rendering his testimony unhelpful and misleading. 

    Statistics Expert Witness

    Alan J. Salzberg Ph.D., is Senior Statistician and Principal of Salt Hill. His focus is statistical analysis, sampling, estimation, and modeling, especially using large or complex datasets. Many of Dr. Salzberg’s consulting projects and research papers have related to the detection and measurement of bias. He has testified as an expert witness in statistics in federal and state court. Prior to joining Salt Hill, Alan was CEO of Analysis & Inference. Salzberg holds a Ph.D. in Statistics from the Wharton School of the University of Pennsylvania, where he also received a Bachelor of Science in Economics.

    Discussions by the Court

    In response to Plaintiffs’ motion to exclude the testimony of Defendants’ expert, Alan Salzberg, the Court engaged in a detailed discussion rooted in the parameters set by Federal Rule of Evidence 702. The Court emphasized that, under Rule 702, the party seeking to introduce expert testimony bore the burden of demonstrating that the testimony met certain criteria, including being based on sufficient facts or data, the product of reliable principles and methods, and reliably applied to the facts of the case. Additionally, the expert’s testimony had to be relevant and assist the jury in understanding the case. 

    The Court considered the motion to exclude the testimony of Alan Salzberg, the Defendants’ expert, who had submitted reports critiquing two of the Plaintiffs’ experts, Andrew Schwarz, an economist, who developed a model to demonstrate the practical implications of elevator outages on passengers traveling on certain high-usage subway routes during rush hours, and Sylvia Morse, Policy Program Manager at Pratt Center for Community Development. The Court began by addressing Salzberg’s expert report titled “Subway Accessibility Analysis.” Salzberg, was tasked with reviewing public elevators in the New York City subway system to determine the elevator, station, and station stop availability for riders with mobility disabilities. Schwarz’s analysis was “intended to highlight the impact of the frequency of inaccessibility calculated by Salzberg on the commutes of targeted types of individuals.”

    In response to Schwarz’s report, Salzberg submitted a reply report on May 2019, using the same Metropolitan Transportation Authority’s (“MTA”) Trip Planner tool that Schwarz relied on for his analysis. Salzberg performed his own analysis of the 200 trips considered by Schwarz and identified errors in Schwarz’s analysis, such as, Schwarz had not selected the 200 subway trips at random and excluded downtown Manhattan stations.

    After the Second Circuit’s remand, Salzberg submitted an update to his report, dated September 12, 2022, concerning accessible elevator, station, and station stop availability, using new data, from 2019 through 2021. In response, Plaintiffs submitted an updated report from Schwarz, dated November 23, 2022. Schwarz, using Salzberg’s statistical calculations, again examined the likelihood that a commuter taking a trip along 200 commuting routes involving subway stations commonly used by passengers with mobility disabilities would experience a failed trip during a particular period of time. The Court noted that Plaintiffs did not challenge Salzberg’s availability calculations, focusing instead on his qualifications and the assumptions underlying his statistical calculations. 

    Plaintiffs argued that Salzberg was unqualified to render an expert opinion in the case due to his lack of expertise in transportation systems, commuting patterns in New York City, or accessibility barriers for people with mobility disabilities. The Court countered this by highlighting that Salzberg analyzed the same data examined by Schwarz, who himself was an economist without expertise in transportation systems. The Court emphasized that Salzberg’s qualifications were appropriate for critiquing Schwarz’s model.

    Another argument raised by Plaintiffs was the unreliability of Salzberg’s methodologies, grounded in alleged flawed assumptions. Plaintiffs contended that these flaws rendered his opinion unreliable and unhelpful to the trier of fact. The Court, however, clarified that criticisms of methodology went to the weight of the expert’s opinion, not its admissibility. The Court stated that faults in methodology were a matter for cross-examination. 

    Plaintiffs specifically challenged Salzberg’s assumption that the MTA’s Trip Planner accurately reflected availability and delays associated with having to reroute or that passengers received timely notification of elevator outages. The Court deemed it reasonable for Salzberg to have relied on data pertaining to route availability and delays, which were maintained by the MTA in the regular course of business and were accessible to the public through the MTA’s Trip Planner online tool. The Court also noted Schwarz’s reliance on the same Trip Planner data in his analysis, highlighting that any inaccuracies would affect both analyses. Plaintiffs’ claims about data inaccuracy were considered arguments concerning the weight of the evidence and not to its admissibility.

    Another point of contention was Salzberg’s definition of a “successful” trip, where Plaintiffs argued that he deemed a trip successful regardless of its duration or onerousness. Salzberg’s use of the Trip Planner tool to determine alternative itineraries was defended by the Court, emphasizing that Plaintiffs could challenge the feasibility of these alternatives on cross-examination. 

    The Court also addressed Salzberg’s consideration of nearby stations when an elevator outage affected the original station, adding travel time to the itinerary whenever necessary. Plaintiffs contended that this introduced selection bias. The Court rejected this argument, stating that Salzberg reliance on the MTA’s Trip Planner to determine alternative itineraries demonstrated no selection bias.

    Moving to the critique of Plaintiffs’ expert Sylvia Morse, the Court outlined the situation. Morse had submitted a rebuttal report focusing on the real-world performance of the bus system and
    factors affecting rider experience, challenging two assumptions made by Salzberg. The first assumption was that transit users with mobility disabilities could always access buses, and the second was that the MTA’s Trip Planner accurately reflected a transit user’s travel time. Ultimately, Morse concluded that accessibility barriers and the unreliability of buses impeded or delayed the completion of alternative itineraries that relied on use of the bus system for transit users with mobility disabilities.  

    In response, Salzberg prepared a rebuttal report criticizing Morse’s reliance on anecdotal customer complaints and arguing that such complaints represented a tiny fraction of all accessible bus trips and was not a statistically valid basis to support a conclusion that the bus system suffered from widespread barriers to accessibility. Plaintiffs challenged Salzberg’s analysis, raising arguments that the Court deemed relevant to the weight of the evidence, not its admissibility.

    Plaintiffs faulted Salzberg for assuming that each complaint concerned only a single ride or bus operator. The Court noted that Plaintiffs had no evidence to support their assumption that a complaint could pertain to multiple trips, highlighting the lack of basis for this criticism. Plaintiffs’ challenge to Salzberg’s conclusion regarding Trip Planner’s notification of elevator outages in real time was also addressed. The Court acknowledged Plaintiffs’ freedom to challenge the persuasiveness of this opinion on cross-examination but found the assumption not unfounded enough to render the opinion inadmissible.

    Held 

    The Court denied the Plaintiffs’ Daubert motion to exclude Dr. Salzberg’s testimony, finding that their criticisms went to the weight rather than the admissibility of his opinions. The Court determined there was no basis to preclude Dr. Salzberg’s expert testimony under the applicable rules of evidence. The Court has not arrived on an outcome for this case since the remaining issues involved in this case still await resolution.

    Key Takeaways

    This case highlights several important considerations regarding the admissibility of expert witness testimony. A key takeaway is that critiques of an expert’s methodology ,sometimes, generally relate to the weight of the testimony rather than its admissibility. The Court emphasized that alleged flaws in an expert’s assumptions or analysis are fodder for cross-examination but do not necessitate exclusion. Furthermore, the ruling demonstrates that rebuttal experts need not have specialized expertise in the substantive field at issue if they are commenting on another expert’s methodology. Finally, the Court highlighted that rebuttal experts should bring specialized knowledge to bear on an issue rather than just speculating or relying solely on anecdotal evidence. These insights shed light on key considerations for expert witness testimony.