Fingerprint error rate on close non‐matches

The accuracy of fingerprint identifications is critically important to the administration of criminal justice. Accuracy is challenging when two prints from different sources have many common features and few dissimilar features. Such print pairs, known as close non‐matches (CNMs), are increasingly likely to arise as ever‐growing databases are searched with greater frequency. In this study, 125 fingerprint agencies completed a mandatory proficiency test that included two pairs of CNMs. The false‐positive error rates on the two CNMs were 15.9% (17 out of 107, 95% C.I.: 9.5%, 24.2%) and 28.1% (27 out of 96, 95% C.I.: 19.4%, 38.2%), respectively. These CNM error rates are (a) inconsistent with the popular notion that fingerprint evidence is nearly infallible, and (b) larger than error rates reported in leading fingerprint studies. We conclude that, when the risk of CNMs is high, the probative value of a reported fingerprint identification may be severely diminished due to an elevated false‐positive error risk. We call for additional CNM research, including a replication and expansion of the present study using a representative selection of CNMs from database searches.     

The Reliability of Pattern Classification in Bloodstain Pattern Analysis,Part 1: Bloodstain Patterns on Rigid Non‐absorbent Surfaces

This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non‐absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed.     

“法律不知有害”质疑

我国大多数学者认为对事实的不知无害,对法律的不知有害,因而实务中对法律错误一般不予以救济。但事实上,不管是在罗马法上,还是在当代的大陆法系和英美法系,大部分国家都会对部分法律错误予以救济。而在确定何种法律错误可予以救济时,应充分考量在特定情况下对表意人"知法推定"的合理性以及表意人与第三人之间的利益衡量。     

Effect of History and Context on Forensic Pathologist Interpretation of Photographs of Patterned Injury of the Skin

In a previous study, a survey‐based analysis of pathologist diagnoses of patterned injury was performed. Subjects were provided with photographs of “classic” injuries and asked to diagnose the lesion in the absence of history or context. There was a relatively low diagnostic consensus among respondents. A second survey suggested that the disparate answers were not due to a strong belief in different diagnoses, but instead reflected how the respondents dealt with ambiguity. A third survey was created that asked participants to evaluate patterned injuries of the skin, but provided history and contextual information. The addition of history and contextual information increased consensus from a median of 80% to 98% on a per‐question basis. Confidence increased from a median of 56%–92%. These results demonstrate the importance of history and context in medical diagnosis of patterned injuries of the skin.     

我国货币供应量与通货膨胀关系实证研究

近期物价上涨已成为人们普遍关心的热点问题,通货膨胀压力在进一步加大。本文选用了2007年-2010年的月度数据,对我国货币供应量M0、M1、M2与通货膨胀的关系进行研究,验证近期货币供应量与通货膨胀之间的具体关系。综合运用协整分析、因果检验以及误差修正模型来揭示我国货币供应量与通货膨胀的长期均衡及短期波动关系,结果显示,货币供应量M1、M2变化是通货膨胀率变化的重要原因。通过调整M1、M2,能够有效控制物价水平的上涨。     

Hair analysis for cocaine: factors in laboratory contamination studies and their relevance to proficiency sample preparation and hair testing practices

Since the introduction in 2001 of a urine-based detection method for recombinant erythropoietin (rHuEPO), transfusion-doping practices have regained interest. To address this problem, an efficient antidoping test designed to obtain direct proof of allogeneic blood transfusion was developed and validated. This test, based on flow cytometry analysis of red blood cell (RBCs) phenotypes, was used to determine the absence or the presence of numerous RBCs populations in a blood sample. A such, it may constitute a direct proof of an abnormal blood population resulting from homologous transfusion. Single-blind and single-site studies were carried out to validate this method as a forensic quality standard analysis and to allow objective interpretation of real cases. The analysis of 140 blood samples containing different percentages (0-5%) of a minor RBCs population were carried on by four independent analysts. Robustness, sensitivity, specificity, precision and stability were assessed. ISO-accredited controls samples were used to demonstrate that the method was robust, stable and precise. No false positive results were observed, resulting in a 100% specificity of the method. Most samples containing a 1.5% minor RBCs population were unambiguously detected, yielding a 78.1% sensitivity. These samples mimicked blood collected from an athlete 3 months after a homologous blood transfusion event where 10% of the total RBCs present in the recipient originated in the donor. The observed false negative results could be explained by differences in antigen expression between the donor and the recipient. False negatives were more numerous with smaller minor RBCs populations. The method described here fulfils the ISO-17025 accreditation and validation requirements. The controls and the methodology are solid enough to determine with certainty whether a sample contains one or more RBCs populations. This variable is currently the best indicator for homologous blood transfusion doping.     

计量经济研究实践中的数据运用误差

计量经济学方法已被广泛地应用于经济研究的各个领域,理论、方法、数据是计量经济研究的三大基本要素。综观国内大量的计量经济研究成果,我们发现不尽严密和科学之处并不少见。本文从数据运用角度,列举了计量经济研究实践中的三类偏误现象,以呼吁人们关注计量经济学研究的客观性     

Effect of Choice of Measure on the Size of a Racial Disparity

In criminological studies of racial disparities the effect of race on outcomes is assessed after statistical controls for other variables. There is no universally accepted measure of size of disparity after controls in the most common type of disparity study: the study of binary outcomes. Some such studies use a measure that lends itself to interpretation in terms of the proportional reduction in error (PRE). Most use a non-PRE measure of association. This study investigates the effect of choice of measure on conclusions about the size of a disparity after controls. For illustrative purposes the study analyzes data on the awarding of sentence reductions to drug traffickers. After controls, blacks are found to be substantially less likely than whites to receive a reduction according to a type of non-PRE measure: an odds ratio derived from a logit model. But using the same data and model, PRE measures obtained from an ROC analysis indicate that, after controls, there is hardly any difference between the races in their likelihood of sentence reduction. Results illustrate the study's thesis: that the choice of measure can powerfully affect conclusions. The findings' implications—for policymakers and for researchers who conduct racial disparity studies—are discussed.     

Firearm examination: Examiner judgments and computer‐based comparisons

Forensic firearm examination provides the court of law with information about the source of fired cartridge cases. We assessed the validity of source decisions of a computer‐based method and of 73 firearm examiners who compared breechface and firing pin impressions of 48 comparison sets. We also compared the computer‐based method's comparison scores with the examiners' degree‐of‐support judgments and assessed the validity of the latter. The true‐positive rate (sensitivity) and true‐negative rate (specificity) of the computer‐based method (for the comparison of both the breechface and firing pin impressions) were 94.4% and at least 91.7%, respectively. For the examiners, the true‐positive rate was at least 95.3% and the true‐negative rate was at least 86.2%. The validity of the source decisions improved when the evaluations of breechface and firing pin impressions were combined and for the examiners also when the perceived difficulty of the comparison decreased. The examiners were reluctant to provide source decisions for "difficult" comparisons even though their source decisions were mostly correct. The correlation between the computer‐based method's comparison scores and the examiners' degree‐of‐support judgments was low for the same‐source comparisons to negligible for the different‐source comparisons. Combining the outcomes of computer‐based methods with the judgments of examiners could increase the validity of firearm examinations. The examiners' numerical degree‐of‐support judgments for their source decisions were not well‐calibrated and showed clear signs of overconfidence. We suggest studying the merits of performance feedback to calibrate these judgments.