Understanding Jurors Use of Highly Diagnostic Statistical Evidence

理解和改进陪审员对高度诊断性统计证据的使用Jonathan J.Koehler在围绕法庭使用科学证据的争议中，没有什么比陪审员如何解释和使用与法医证据有关的微小统计数据更紧迫的问题。例如，许多人认为，在犯罪嫌疑人与从暴力犯罪现场找到的DNA证据的痕迹相匹配的情况下，这些统计数据是有说服力的。也就是说，他们认为，在听到从千分之一到十亿分之一的巧合匹配统计数据后，陪审员将确信匹配的嫌疑人确实是恢复的DNA证据的来源。其他人认为陪审员会被数字搞糊涂，不会发现令人信服的证据。谁是对的？我自己对模拟陪审员进行的初步研究表明，提供统计证据的方式可能会对法律决策者如何思考和使用证据产生强大的影响。我提供了一个描述性理论和两个实验来帮助理解法律决策者如何应对高度诊断性的统计证据。这个理论--称为样本提示理论--预测决策者何时会发现统计匹配证据相对有力和有说服力，以及何时不会。它认为，与统计匹配证据的强度和说服力有关的判断和选择是由巧合匹配样本的可用性来指导的。在决策者可以很容易地产生偶然匹配的例子的程度上，证据作为身份证明似乎不那么令人信服。这个理论框架足够广泛，可以理解人们是如何思考许多小概率事件的，比如一个人中彩票的机会，或者环境灾难或遗传病带来的风险。它还足够精炼，可以帮助我们理解陪审员何时会被被告的论点说服，即DNA匹配纯粹是巧合。这些数据将对各种选民有用，从必须为统计证据的可采性制定指令和标准的法官和政策制定者，到必须找到方法传达匹配含义的科学家、执法人员和律师。

Understanding and Improving Jurors' Use of Highly Diagnostic Statistical EvidenceJonathan J. KoehlerThere is no more pressing issue in the controversy that swirls around the use of scientific evidence in the courtroom than how jurors interpret and use the tiny statistics that arise in connection with forensic science evidence. For example, many people assume that these statistics are persuasive in cases where a criminal suspect matches traces of DNA evidence recovered from the scene of a violent crime. That is, they believe that after hearing coincidental match statistics that range from 1 in thousands to 1 in billions, jurors will be convinced that the matching suspects are indeed the source of the recovered DNA evidence. Others believe that jurors will be confused by the numbers and will not find the evidence compelling.Who's right? My own preliminary research with mock jurors indicates that the way in which statistical evidence is presented may exert a powerful effect on how legal decision makers think about and use the evidence. I offer a descriptive theory and two experiments to help understand howlegal decision makers respond to highly diagnostic statistical evidence.The theory -- called exemplar cueing theory -- predicts when decisionmakers will find statistical match evidence relatively strong andpersuasive and when not. It holds that judgments and choices related tothe strength and persuasiveness of statistical match evidence are guided bythe availability of coincidental match exemplars. To the extent decisionmakers can easily generate examples of chance matches, the evidence willseem less compelling as proof of identity. This theoretical framework is broad enough for understanding how peoplethink about many low probability events such as one's chances of winningthe lottery or the risks posed by environmental catastrophe or geneticdisease. It is also sufficiently refined that it may help us understandwhen jurors will be persuaded by a defendant's argument that a DNA match ispurely coincidental.These data will be useful to a variety of constituencies, from the judgesand policy makers who must develop instructions and standards for theadmissibility of statistical evidence, to the scientists, law enforcementofficers, and attorneys who must find ways to communicate the meaning of amatch.