Statistical Testimony Research Articles

Call Mr. Fisher

Expert statistical testimony has come a long way since a judge characterized Fisher’s Exact Test as “hearsay” and demanded that Mr. Fisher be called to testify.1 Indeed, since the O.J. Simpson tria...

The Role of Statistical Evidence in Civil Cases

Civil cases outnumber criminal cases in federal courts, and statistical evidence has become more important in a wide variety of them. In contrast to science, which is concerned with general phenomena, legal cases concern one plaintiff or a class of plaintiffs and replication of the events that led to the case is not possible. This review describes the legal process, the way statistics are used in several types of cases, and the criteria courts use in evaluating the reliability of statistical testimony. Several examples of courts’ misinterpreting statistical analyses are presented. Commonly occurring issues in the statistical analysis of stratified data, the use of regression analysis, and the use of epidemiologic estimates of relative risk are described. Hopefully, this review will encourage statisticians to engage with the legal system and develop better ways of communicating the results of studies so they receive the evidentiary weight they deserve.

Executing Daniel Bright: Race, Loyalty, and Guerrilla Violence in a Coastal Carolina Community, 1861–1865 by Barton A. Myers (review)

Reviewed by: Executing Daniel Bright: Race, Loyalty, and Guerrilla Violence in a Coastal Carolina Community, 1861–1865 by Barton A. Myers Robert Tracy McKenzie (bio) Executing Daniel Bright: Race, Loyalty, and Guerrilla Violence in a Coastal Carolina Community, 1861–1865. By Barton A. Myers. (Baton Rouge: Louisiana State University Press, 2009. Pp. 193. Cloth, $32.50; paper, $18.95.) According to Barton Myers, the germ of this book can be traced to the moment when, as an undergraduate engaged in library research at the University of North Carolina, the author stumbled across a brief newspaper account of the execution by Union soldiers of a suspected Confederate guerrilla in northeastern North Carolina. A few years later, by then a master’s degree candidate in graduate school, Myers resolved to revisit the episode with the goal of understanding the community from which the alleged insurgent came. The result is a brief, well-crafted monograph that offers tantalizing insight into the nature and consequences of guerrilla violence in a divided southern community. [End Page 418] As is often the case with academic works, the focus of the book is captured in its subtitle, not its title. Indeed, the reference to the execution of Daniel Bright is essentially a literary device. In truth, Myers could learn little about the alleged insurgent beyond the statistical testimony left by the federal census. Bright was approximately thirty at the time of his execution in December 1863. On the eve of the war, he had owned an estimated $4,500 worth of real and personal property, including one slave. Because Bright left no personal papers behind, not even a military service record, Myers can only conjecture why Bright enrolled in the Confederate service in 1861, why he may have returned home when his original twelve-month term was up, and why he may have later reenlisted and then, possibly, deserted to become, perhaps, a Confederate guerilla in his home community. Nor is much known about Bright’s trial and execution during a counterguerrilla raid led by Union general Augustus Wild. The note that Wild pinned to Bright’s corpse labeled the deceased a guerrilla, and although Confederate authorities disputed the allegation, Myers ultimately concludes that it was “very likely” that Wild was correct (97). The verdict is plausible, yet the evidence for even this basic detail is mostly indirect and circumstantial. Myers has done the best that he can with what he has to work with, but that, unfortunately, is not very much. Myers is much more successful at explaining the context—physical and cultural—in which the trial and execution took place. Executing Daniel Bright is primarily a careful analysis of Pasquotank County, North Carolina, and the economic, social, political, and racial milieu within which local guerrillas operated. The author stresses three themes. The first involves the continuing importance of antebellum political patterns. Although moribund nationally, the two-party system was still alive and well in Pasquotank, and the free population divided during the early stages of the secession crisis along partisan lines, its large Whig majority opposing the prosecession, Democratic minority. After Fort Sumter, all but perhaps 5 percent of the white population became Confederates, but erstwhile Whigs were always primarily loyal to North Carolina—rather than to the Confederacy per se—and the county as a whole never developed a robust Confederate nationalism. In contrast, whites were definitely unified in their fear of racial upheaval, the second theme that Myers identifies. Their anxiety was heightened by the sheer size of the local black population (slaves and free blacks slightly outnumbered whites) and by their proximity to the Great Dismal Swamp, an ideal haven for fugitives. Finally, Myers stresses that much of the county was a “no-man’s land” after the spring of 1862, the area perpetually subject to Union raids but effectively [End Page 419] controlled by neither army. In this vacuum of power, guerrillas often operated with impunity. Perhaps the greatest strength of the work is the author’s careful treatment of the impact and significance of General Wild’s raid on the county. By leading a brigade of United States Colored Troops into Pasquotank, including some former local slaves, the raid embodied...

If the Shoe Fits They Might Acquit: The Value of Forensic Science Testimony

The probative value of forensic science evidence (such as a shoeprint) varies widely depending on how the evidence and hypothesis of interest is characterized. This article uses a likelihood ratio (LR) approach to identify the probative value of forensic science evidence. It argues that the “evidence” component should be characterized as a “reported match,” and that the hypothesis component should be characterized as “the matching person or object is the source of the crime scene sample.” This characterization of the LR forces examiners to incorporate risks from sample mixups and examiner error into their match statistics. But will legal decisionmakers be sensitive to the extent to which examiners' statistical testimony accounts for various potential sources of risk and error? A controlled experiment with 315 jury‐eligible jurors who received a shoeprint match statistic in a hypothetical burglary case finds that, contrary to normative theory, people are more persuaded by statistical testimony that ignores various error risks than by testimony that is objectively stronger by virtue of taking those risks into account. The experiment also finds that jurors are relatively unresponsive to exposure of those risks by a defense attorney on cross‐examination. These results support and extend previous research that finds many people are confused about how to evaluate the risk of error associated with expert forensic testimony.

Some issues arising in the presentation of statistical testimony

This article describes some special problems facing expert witnesses presenting statistical evidence when they testify in court. Since the legal system, especially in civil cases, serves as a dispute resolution process that needs to reach a decision in a timely manner, its objectives and procedures differ from those in pure science. Unlike the classroom or summarizing their research in a talk where the statistician determines the presentation, in the courtroom a witness is only allowed to answer questions posed by the others, mainly the lawyers for both parties. One case where the author could not persuade the lawyer to ask a set of questions designed to show that the other ‘expert’ was using a statistical that had no power and consequently would never indicate that the data were consistent with discrimination is described. In contrast, a case where the judge understood the need for the data analysis to correspond to the time frame of the case and accepted the Mantel–Haenszel test as an appropriate way to analyse stratified data arising in a discrimination case is summarized. Several suggestions designed to improve the effectiveness of statistical testimony and related issues arising in Daubert hearings that screen proposed expert analyses for scientific reliability are given. Recently, a distinguished scientist wrote an editorial in Science that supported epidemiologists who had obtained data solely for use in a case but later submitted an article to a journal, apparently in violation of the court’s order. The last section questions this view as it diminishes the value of commitments researchers give the public when they obtain information about individuals and recommends that statisticians obtain permission to write an article based on their research at the time they are engaged.

Rethinking Expert Testimony in Education Rights Litigation

Courts often rely on the testimony of experts to understand arguments and implications in education rights litigation. But expert testimony, and statistical testimony in particular, can offer a false sense of security for the unwary. This article uses expert testimony offered in two recent desegregation cases to consider whether sufficient protections are presently in place to protect judges, who are usually statistical novices, from being confused or misled by experts. These case studies illustrate how, without the use of additional protections, courts can be misled. Following this examination, we offer suggestions intended to improve judges’ comprehension of expert testimony. At its most general level, this article addresses the role of researchers in presenting important educational issues in ways that speak clearly to policy-makers.

Expert statistical testimony and epidemiological evidence: the toxic effects of lead exposure on children

The past two decades have seen a dramatic growth in the use of statisticians and economists for the presentation of expert testimony in legal proceedings. In this paper, we describe a hypothetical case modeled on real ones and involving statistical testimony regarding the causal effect of lead on lowering the IQs of children who ingest lead paint chips. The data we use come from a well-known pioneering study on the topic and the analyses we describe as the expert testimony are similar to ones that can be found in, major scientific journals. The battle of the experts in this hypothetical case resembles that which many encounter as expert witnesses. The paper concludes with some observations and advice.

The Significance of Quantitative Evidence in Federal Trade Commission Deceptive Advertising Cases

The Federal Trade Commission (FTC) has no guidelines for the development, presentation, and evaluation of statistical evidence by litigators or administrative law judges in deceptive advertising cases.l As a result, Commission opinions and evidentiary findings related to statistical testimony run to hundreds of pages, discouraging the most determined reader, while orders emerging from the decisions are vague as to their implications for statistical proof of a reasonable basis for making an advertising claim. Statistical evidence is nothing new to the hearing examiners, who were considering quantitative arguments in both unfair competition2 and unfair trade practice3 cases even before Title VII came into effect,4 which gave rise to the tremendous growth in quantitative analysis in employment discrimination law. The increasing sophistication of lawyers, who are growing accustomed to complex tools of statistical inference in discrimination cases,5 and changes in the law, particularly in the commercial speech area, suggests that an examination of the process by which litigators present and judges evaluate quantitative evidence is appropriate.6 The elevation of commercial speech to a constitutionally protected status