Biostatistics & Statistics Expert Witness
Biostatistics Expert Witness — Former FDA/CDRH Statistical Reviewer
Lei Li, Ph.D., is a biostatistician and former FDA/CDRH primary statistical reviewer who helps plaintiff and defense counsel evaluate adverse-event analyses, clinical-trial evidence, and FDA clearance and regulatory questions — with opinions grounded in the data and built to withstand Daubert and cross-examination.
- Former FDA primary statistical reviewer
- Ph.D. Biostatistics (George Mason)
- Plaintiff & defense
- Subject to conflicts check
Why a Former FDA Statistical Reviewer
An inside view of how the FDA weighs statistical evidence
As a primary statistical reviewer at FDA's Center for Devices and Radiological Health, Dr. Li evaluated the statistical evidence behind medical-device submissions. That experience is rare among testifying statisticians — and directly relevant when a case turns on regulatory data or methodology.
Regulatory insight
Firsthand knowledge of how FDA actually evaluates statistical evidence in PMA, De Novo, 510(k), IDE, and real-world-evidence submissions.
Plain-language clarity
Translates complex statistical and regulatory concepts into terms judges, juries, and counsel can follow and rely on.
Daubert-ready opinions
Analysis grounded in real regulatory practice and generally accepted methodology — prepared to withstand cross-examination and FRE 702 scrutiny.
What "primary reviewer" meant
Reviewed submissions, authored statistical memoranda, and applied the agency's statistical standards to therapeutic and diagnostic devices.
Dr. Li is a former mathematical statistician with the FDA/CDRH (2020–2022). He is no longer affiliated with the FDA; this site is not affiliated with, endorsed by, or sponsored by the FDA or any government agency, and nothing here represents the views of the FDA.
Areas of Expertise
Statistical expertise mapped to your matter
Whether the dispute turns on a clinical trial, a device clearance, an adverse-event rate, or an opposing expert's methodology, Dr. Li brings directly relevant experience.
Clinical-trial design & analysis
Phase I–IV design and analysis, endpoints, Bayesian, adaptive, and group-sequential designs, and efficacy/safety disputes.
FDA regulatory & clearance
510(k), PMA, De Novo, and IDE submissions, clearance-probability questions, and regulatory methodology — from a former reviewer's perspective.
Medical-device statistics & RWE
Premarket statistical evidence, real-world evidence, and propensity-score methodology for device litigation.
Adverse-event & pharmacovigilance
Incidence-rate and safety-signal analysis, number-needed-to-harm, and evaluation of FAERS and trial safety data.
Epidemiology & causation
Relative risk and "doubling of risk," confounding, Bradford Hill considerations, and general vs. specific causation in toxic-tort matters.
Rebuttal & methodology critique
Independent critique of opposing experts' study designs, assumptions, statistical methods, and conclusions.
Litigation Support Services
Two ways to retain a statistical expert
From early case assessment through trial testimony — engaged in whichever role the matter calls for.
Strategy & case assessment
- Early case assessment of statistical strengths and weaknesses
- Independent review of study designs and statistical methods
- Identifying weaknesses in an opposing analysis
- FDA regulatory and evidence-strategy review (incl. 505(b)(2) considerations)
Reports & testimony
- Expert reports, declarations, and affidavits
- Rebuttal of opposing statistical experts
- Daubert / admissibility support
- Deposition and trial testimony
About
About Lei Li, Ph.D.
Lei Li, Ph.D., is a biostatistician and former FDA/CDRH mathematical statistician who served as a primary statistical reviewer for medical-device submissions, including PMA, De Novo, 510(k), and IDE applications. He now provides independent statistical consulting and expert-witness services to attorneys, helping both plaintiff and defense counsel evaluate adverse-event analyses, clinical-trial evidence, FDA clearance questions, and disputed statistical methodology.
He brings the rare combination of inside-the-agency regulatory perspective and hands-on industry experience across both medical devices (Edwards Lifesciences) and pharmaceuticals (Sanofi), and maintains an active research program in clinical-trial design and statistical methodology.
Engagements are provided through his firm, LunarAI LLC. A full CV is available on request.
Representative Matters & Methods
Experience described by matter type — never by client
Dr. Li does not disclose the identity of parties, counsel, courts, or any confidential materials from prior engagements.
Adverse-event incidence & FDA clearance methodology
Retained to evaluate adverse-event incidence analyses and to assess FDA clearance-probability calculations and related statistical methodology, assisting counsel with the statistical, device, and regulatory issues at the center of the matter.
▪ ConfidentialEvidence-generation strategy & regulatory pathway
Retained to evaluate an evidence-generation strategy and the associated FDA regulatory considerations, including assessment of clinical and biomarker evidence gaps and 505(b)(2)-pathway considerations.
▪ ConfidentialDisclosed litigation engagements to date have been in consulting-expert roles. Dr. Li is available for, and welcomes, testifying-expert engagements, including declarations, affidavits, deposition, and trial testimony.
Independent, Methodology-Driven Analysis
A deliberately manageable caseload, active research, and work for both plaintiff and defense are how Dr. Li keeps his analysis credible and his testimony persuasive.
Insights & Articles
Plain-language explainers on the statistics behind litigation
Educational writing on the recurring statistical questions that decide medical-device, pharmaceutical, and clinical-trial cases.
Relative Risk > 2 and Specific Causation
What the "doubling of the risk" argument really means, why some courts treat it as a threshold, and where the inference breaks down.
Read article →Daubert and Statistical Evidence
What attorneys should know about how statistical opinions are tested for reliability under FRE 702.
Coming soonInterpreting Adverse-Event Rates
Number needed to harm, incidence rates, and the common ways adverse-event data are misread in litigation.
Coming soonFrequently Asked Questions
What attorneys ask first
What kind of expert witness is Lei Li, Ph.D.?
Dr. Li is a biostatistics and statistics expert witness and a former FDA/CDRH mathematical statistician (primary statistical reviewer). He provides independent statistical analysis, expert reports, declarations, deposition, and trial testimony in litigation involving medical devices, pharmaceuticals, clinical trials, adverse-event and incidence analysis, and FDA regulatory and clearance questions.
Does Dr. Li work for plaintiffs or for the defense?
Both. He is available to plaintiff and defense counsel and forms his opinions from the data and generally accepted statistical methodology regardless of which party retains him. Every prospective engagement is subject to a conflicts-of-interest check before it can be accepted.
What does his former FDA experience add to a case?
As a primary statistical reviewer at FDA's Center for Devices and Radiological Health, he evaluated premarket submissions including PMA, De Novo, 510(k), IDE, and real-world-evidence studies. That gives him firsthand insight into how the agency actually weighs statistical evidence. He is a former employee, no longer affiliated with the FDA, and the FDA does not endorse or sponsor his services.
What types of matters and methods does he cover?
Adverse-event incidence and safety-signal analysis, clinical-trial design and analysis (including Bayesian, adaptive, and group-sequential designs), FDA regulatory and clearance questions, real-world evidence and propensity-score methods, epidemiology and causation/relative-risk analysis, survival analysis, statistical sampling, and critique or rebuttal of opposing experts' methodology.
Will his testimony hold up under a Daubert challenge?
His opinions are grounded in the data and generally accepted statistical methodology and are prepared to be defensible under Federal Rule of Evidence 702 and Daubert. No expert can guarantee admissibility or any particular result; each matter is evaluated independently on its own facts and the applicable standards.
How quickly can he assess a new matter, and what should I send?
Reach out through the contact form, by email, or by phone for a confidential, no-obligation initial discussion and conflicts check. Please do not send confidential, privileged, or case-specific material until a conflicts check is completed and an engagement is confirmed in writing; until then no duty of confidentiality arises.
What are his credentials?
Ph.D. in Statistics (George Mason University) and M.S. in Statistics (George Washington University); former FDA/CDRH mathematical statistician and primary statistical reviewer; Principal Biostatistician at Edwards Lifesciences and Statistical Project Leader at Sanofi; peer-reviewed author and invited speaker with an active research program. A full CV is available on request.
Has he testified at deposition or trial before?
His disclosed litigation engagements to date have been in consulting-expert roles, and he is available and welcomes testifying-expert engagements, including declarations, affidavits, deposition, and trial testimony. He describes prior matters only in general terms and does not disclose parties or confidential materials.
Does contacting Dr. Li create an engagement or confidential relationship?
No. Visiting the site or submitting an inquiry does not create any attorney-client, consulting, or expert-witness relationship, and no duty of confidentiality arises until a written engagement agreement is signed and a conflicts-of-interest check is cleared.
Request a Confidential Case Consultation
Discuss your matter with Dr. Li
A confidential, no-obligation initial discussion — subject to a conflicts-of-interest check. Tell us a little about the matter and Dr. Li will respond to you directly.
(202) 341-8398
info@lunarai.llc
Serving clients nationwide (U.S.)
Prefer to call? Dr. Li is happy to have a brief, confidential scoping conversation before any engagement or exchange of case materials.