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Power And Statistical Significance In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach Jan 2021

Power And Statistical Significance In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach

Faculty Scholarship at Penn Law

Event studies, a half-century-old approach to measuring the effect of events on stock prices, are now ubiquitous in securities fraud litigation. In determining whether the event study demonstrates a price effect, expert witnesses typically base their conclusion on whether the results are statistically significant at the 95% confidence level, a threshold that is drawn from the academic literature. As a positive matter, this represents a disconnect with legal standards of proof. As a normative matter, it may reduce enforcement of fraud claims because litigation event studies typically involve quite low statistical power even for large-scale frauds.

This paper, written for ...


Digging Into The Foundations Of Evidence Law, David H. Kaye Apr 2017

Digging Into The Foundations Of Evidence Law, David H. Kaye

Michigan Law Review

Review of The Psychological Foundations of Evidence Law by Michael J. Saks and Barbara A. Spellman.


Evidence Of Child Abuse: Inferring The Causes Of Effects, Stephen E. Fienberg Mar 2017

Evidence Of Child Abuse: Inferring The Causes Of Effects, Stephen E. Fienberg

University of Michigan Journal of Law Reform

A statistician's take on evidence of child abuse.


Problems With Using Statistics To Justify Institutional Policies, Justin Shin Jan 2017

Problems With Using Statistics To Justify Institutional Policies, Justin Shin

Senior Projects Spring 2017

It is becoming increasingly common for institutions to use statistics to inform policy decisions. We should be prepared to ask ourselves what regulatory principles should be imposed on institutions that seek to justify certain policies through deference to a statistical analysis. This paper will examine the difficulties that come with using statistics to justify actions, and argue that certain standards of transparency and verifiability should be expected from any institution that seeks to involve a statistical analysis in the formation of policies. I will first use Market Share Liability, an established use of statistics, to draw out what responsibilities an ...


Statistical Significance And The Burden Of Persuasion, David H. Kaye Mar 2016

Statistical Significance And The Burden Of Persuasion, David H. Kaye

David Kaye

In most endeavors concerned with the acquisition of knowledge, quantitative information is welcomed. In law, however, it appears sometimes that scientific or numerical evidence makes cases harder, not easier. Nevertheless, there are many cases and administrative proceedings, in such areas as environmental law, food and drug regulation, and civil rights, in which statistical data obtained by observation or experiment are readily accepted as assisting in the proper resolution of disputed issues of fact. When courts or administrators confront scientific and statistical evidence in these proceedings, they are not always certain of how to weigh the evidence or whether they should ...


Experts, Statistics, Science & Bad Science, Curtis E.A. Karnow Nov 2015

Experts, Statistics, Science & Bad Science, Curtis E.A. Karnow

Curtis E.A. Karnow

Articles, books, and other online resources relating to expert testimony with a specific focus on problems with peer review, bad science, and statistics


Visualizing Probabilistic Proof, Enrique Guerra-Pujol Nov 2014

Visualizing Probabilistic Proof, Enrique Guerra-Pujol

Washington University Jurisprudence Review

The author revisits the Blue Bus Problem, a famous thought-experiment in law involving probabilistic proof, and presents Bayesian solutions to different versions of the blue bus hypothetical. In addition, the author expresses his solutions in standard and visual formats, that is, in terms of probabilities and natural frequencies.


The Discoverability Of E-Mails: The Smoking Gun Of The Modern Era, Michael J. Martin Mar 2014

The Discoverability Of E-Mails: The Smoking Gun Of The Modern Era, Michael J. Martin

University of Massachusetts Law Review

The discoverability of e-mails is an area of law that every modern day lawyer must be familiar with in order to avoid the risk of being sanctioned. Over the past years, courts have awarded sanctions to moving parties at a steadily increasing pace. These sanctions have included adverse jury instructions, default judgements, attorney's fees, large monetary fines, and in one instance, a jail sentence. Courts have sent the message that improper conduct will not be tolerated in this developing area of law by not hesitating to order sanctions. Thus, it is essential that modern day lawyers become acquainted with ...


When 10 Trials Are Better Than 1000: An Evidentiary Perspective On Trial Sampling, Edward K. Cheng Jan 2012

When 10 Trials Are Better Than 1000: An Evidentiary Perspective On Trial Sampling, Edward K. Cheng

Vanderbilt Law School Faculty Publications

In many mass tort cases, separately trying all individual claims is impractical, and thus a number of trial courts and commentators have explored the use of statistical sampling as a way of efficiently processing claims. Most discussions on the topic, however, implicitly assume that sampling is a “second best” solution: individual trials are preferred for accuracy, and sampling only justified under extraordinary circumstances. This Essay explores whether this assumption is really true. While intuitively one might think that individual trials would be more accurate at estimating liability than extrapolating from a subset of cases, the Essay offers three ways in ...


Proposal To Reverse The View Of A Confession: From Key Evidence Requiring Corroboration To Corroboration For Key Evidence, Boaz Sangero, Mordechai Halpert Apr 2011

Proposal To Reverse The View Of A Confession: From Key Evidence Requiring Corroboration To Corroboration For Key Evidence, Boaz Sangero, Mordechai Halpert

University of Michigan Journal of Law Reform

Both case law and legal literature have recognized that all, and not just clearly statistical, evidence is probabilistic. Therefore, we have much to learn from the laws of probability with regard to the evaluation of evidence in a criminal trial. The present Article focuses on the confession. First, we review legal and psychological literature and show that the probability of a false confession and, consequently, a wrongful conviction, is far from insignificant. In light of this, we warn against the cognitive illusion, stemming from the fallacy of the transposed conditional, which is liable to mislead the trier of fact in ...


Statistics In Law: Bad Inferences & Uncommon Sense, Curtis E.A. Karnow Jan 2011

Statistics In Law: Bad Inferences & Uncommon Sense, Curtis E.A. Karnow

Curtis E.A. Karnow

A review of classic fallacies in statistics and probability in the courts. The article briefly, and in plain English, provides an introduction to probability theory, and randomness.


Will Quants Rule The (Legal) World?, Edward K. Cheng Jan 2009

Will Quants Rule The (Legal) World?, Edward K. Cheng

Vanderbilt Law School Faculty Publications

Professor Ian Ayres, in his new book, Super Crunchers, details the brave new world of statistical prediction and how it has already begun to affect our lives. For years, academic researchers have known about the considerable and at times surprising advantages of statistical models over the considered judgments of experienced clinicians and experts. Today, these models are emerging all over the landscape. Whether the field is wine, baseball, medicine, or consumer relations, they are vying against traditional experts for control over how we make decisions. For the legal system, the take-home of Ayres's book and the examples he describes ...


Revisiting 'Dreyfus': A More Complete Account Of A Trial By Mathematics, David H. Kaye Jan 2007

Revisiting 'Dreyfus': A More Complete Account Of A Trial By Mathematics, David H. Kaye

Journal Articles

Legal literature and case law depicts the infamous conviction of Alfred Dreyfus for treason and espionage in 1899 as a prime example of the irresistible power of even grossly fallacious mathematical demonstrations to overwhelm a legal tribunal. This essay shows that Dreyfus is not a case of mathematics run amok, unchecked and uncomprehended. To the contrary, the defects in the mathematical proof were dramatically exposed, and this evidence did not lead Dreyfus's judges to condemn him. This history undercuts the reliance of modern courts and commentators on Dreyfus as an indication or illustration of the alleged dangers of probability ...


Bayes' Law, Sequential Uncertainties, And Evidence Of Causation In Toxic Tort Cases, Neal C. Stout, Peter A. Valberg Jul 2005

Bayes' Law, Sequential Uncertainties, And Evidence Of Causation In Toxic Tort Cases, Neal C. Stout, Peter A. Valberg

University of Michigan Journal of Law Reform

Judges are the gatekeepers of evidence. Arguably, the most difficult duty for a judicial gatekeeper is to screen the reliability of expert opinions in scientific fields such as medicine that are beyond the ken of most judges. Yet, judges have a duty to scrutinize such expert opinion evidence to determine its reliability and admissibility. In toxic tort cases, the issue of causation-whether the alleged exposures actually caused the plaintiffs injury-is nearly always the central dispute, and determining admissibility of expert causation opinion is a daunting challenge for most judges. We present a comprehensive review of the courts' struggles with the ...


Sometimes What Everybody Thinks They Know Is True, Richard D. Friedman, Roger C. Park Jan 2003

Sometimes What Everybody Thinks They Know Is True, Richard D. Friedman, Roger C. Park

Articles

This essay responds to D. Davis and W. C. Follette (2002), who question the value of motive evidence in murder cases. They argue that the evidence that a husband had extramartial affairs, that he heavily insured his wife's life, or that he battered his wife is ordinarily of infinitesimal probative value. We disagree. To be sure, it would be foolish to predict solely on the basis of such evidence that a husband will murder his wife. However, when this kind of evidence is cobmined with other evidence in a realistic murder case, the evidence can be quite probative. We ...


Conjunction And Aggregation, Saul Levmore Feb 2001

Conjunction And Aggregation, Saul Levmore

Michigan Law Review

This Article begins with the puzzle of why the law avoids the issue of conjunctive probability. Mathematically inclined observers might, for example, employ the "product rule," multiplying the probabilities associated with several events or requirements in order to assess a combined likelihood, but judges and lawyers seem otherwise inclined. Courts and statutes might be explicit about the manner in which multiple requirements should be combined, but they are not. Thus, it is often unclear whether a factfinder should assess if condition A was more likely than not to be present - and then go on to see whether condition B satisfied ...


Dna As Evidence: Viewing Science Through The Prism Of The Law, Peter Donnelly, Richard D. Friedman Jan 2000

Dna As Evidence: Viewing Science Through The Prism Of The Law, Peter Donnelly, Richard D. Friedman

Articles

In this article, we analyze a problem related to DNA evidence that is likely to be of great and increasing significance in the near future. This is the problem of whether, and how, to present evidence that the suspect has been identified through a DNA database search. In our view, the two well-known reports on DNA evidence issued by the National Research Council (NRC) have been badly mistaken in their analysis of this problem. The mistakes are significant because the reports have carried great authority with American courts; moreover, the DNA Advisory Board of the FBI has endorsed the second ...


Dna Database Searches And The Legal Consumption Of Scientific Evidence, Peter Donnelly, Richard D. Friedman Jan 1999

Dna Database Searches And The Legal Consumption Of Scientific Evidence, Peter Donnelly, Richard D. Friedman

Articles

DNA evidence has transformed the proof of identity in criminal litigation, but it has also introduced daunting problems of statistical analysis into the process. In this Article, we analyze a problem related to DNA evidence that is likely to be of great and increasing significance in the near future. This is the problem of whether, and how, to present evidence that the suspect has been identified through a DNA database search. In our view, the two well-known reports on DNA evidence issued by the National Research Council ("NRC"), each of which has carried great authority with the American courts on ...


Assessing Evidence, Richard D. Friedman Jan 1996

Assessing Evidence, Richard D. Friedman

Reviews

David A. Schum's Evidential Foundations of Probabilistic Reasoning, 2 C.G.G. Aitken's Statistics and the Evaluation of Evidence for Forensic Scientists,3 and Bernard Robertson and G.A. Vignaux's Interpreting Evidence: Evaluating Forensic Science in the Courtroom4 all have something to tell us about how to use and evaluate evidence. Although the books are addressed to different primary audiences5 and their authors come from a variety of disciplines and from distant points of the English-speaking world,6 all three help draw the connection between underlying theory and presentation in the courtroom. Though Schum uses numerous examples ...


Probability And Proof In State V. Skipper: An Internet Exchange, Ronald J. Allen, David J. Balding, Peter Donnelly, Richard D. Friedman, David H. Kaye, Lewis Henry Larue, Roger C. Park, Bernard Robertson, Alexander Stein Jan 1995

Probability And Proof In State V. Skipper: An Internet Exchange, Ronald J. Allen, David J. Balding, Peter Donnelly, Richard D. Friedman, David H. Kaye, Lewis Henry Larue, Roger C. Park, Bernard Robertson, Alexander Stein

Articles

This is not a conventional article. It is an edited version of messages sent to an Internet discussion list. The listings begin with the mention of a recent opinion of the Connecticut Supreme Court, parts of which are reproduced below. The listings soon move to broader issues concerning probability and other formal systems, their limitations, and their uses either in court or as devices for understanding legal proof.


Stories Versus Theories At The Cardozo Evidence Conference: It's Just Another Metaphor To Me, Lewis H. Larue Aug 1992

Stories Versus Theories At The Cardozo Evidence Conference: It's Just Another Metaphor To Me, Lewis H. Larue

Scholarly Articles

Not available.


Webs Of Things In The Mind: A New Science Of Evidence, Peter Tillers May 1989

Webs Of Things In The Mind: A New Science Of Evidence, Peter Tillers

Michigan Law Review

A Review of Evidence and Inference for the Intelligence Analyst by David Schum


Statistical Significance And The Burden Of Persuasion, David H. Kaye Jan 1983

Statistical Significance And The Burden Of Persuasion, David H. Kaye

Journal Articles

In most endeavors concerned with the acquisition of knowledge, quantitative information is welcomed. In law, however, it appears sometimes that scientific or numerical evidence makes cases harder, not easier. Nevertheless, there are many cases and administrative proceedings, in such areas as environmental law, food and drug regulation, and civil rights, in which statistical data obtained by observation or experiment are readily accepted as assisting in the proper resolution of disputed issues of fact. When courts or administrators confront scientific and statistical evidence in these proceedings, they are not always certain of how to weigh the evidence or whether they should ...


Statistics In The Potential Problems In The Presentation Of Statistical Evidence Jan 1983

Statistics In The Potential Problems In The Presentation Of Statistical Evidence

Washington and Lee Law Review

No abstract provided.


The Numbers Game: Statistical Inference In Discrimination Cases, David H. Kaye Mar 1982

The Numbers Game: Statistical Inference In Discrimination Cases, David H. Kaye

Michigan Law Review

A Review of Statistical Proof of Discrimination by David Baldus and James Cole