Assessment of approximate likelihood ratios from continuous distributions: a case study of digital camera identification

A reported likelihood ratio for the value of evidence is very often a point estimate based on various types of reference data. When presented in court, such frequentist likelihood ratio gets a higher scientific value if it is accompanied by an error bound. This becomes particularly important when the magnitude of the likelihood ratio is modest and thus is giving less support for the forwarded proposition. Here, we investigate methods for error bound estimation for the specific case of digital camera identification. The underlying probability distributions are continuous and previously proposed models for those are used, but the derived methodology is otherwise general. Both asymptotic and resampling distributions are applied in combination with different types of point estimators. The results show that resampling is preferable for assessment based on asymptotic distributions. Further, assessment of parametric estimators is superior to evaluation of kernel estimators when background data are limited.     

Study of poroscopy among South Indian population

Poroscopy is the term applied to a specialized study of pore structure found on papillary ridges of skin as a means of identification. It comes under level 3 detail of identification and hence is more reliable and accurate. The goal of this study is to estimate the importance of poroscopy for identification of individuals and to determine the gender based on frequency, type, and shape of pores. Left plain thumb prints of 200 individuals (100 men and 100 women) aged between 18 and 60 belonging to South Indian population were observed. The results have shown that women tend to have a significantly higher frequency of pores than men. Number of pores ≤ 8 pores/25 mm(2) is more likely to be of male origin and ≥9 pores/25 mm(2) is more likely to be of female origin. There was no significant sex difference based on type and shape of pores.     

Utility of the Frontonasal Suture for Estimating Age at Death in Human Skeletal Remains*

Abstract: This project evaluated the utility of the frontonasal suture for estimating age at death. Utilizing human remains of known age at death with varying degrees of fusion, curated at the American Museum of Natural History in New York City and the Smithsonian Institution’s National Museum of Natural History in Washington, DC, data were collected from the ectocranial surface of 522 crania; 68 of these were sagittally sectioned, allowing collection of internal data and observation of suture closure through the bone. Degree of ectocranial suture closure does not significantly predict age, even when sex and ancestry are accounted for. Suture closure progression data were converted into a Hershkovitz ratio (sum of the measurement of open portion divided by the total suture length), and regression models demonstrate that the effect of age accounts for only 13% of variation in suture closure.     

A large-scale study of the relationship between blood and breath alcohol concentrations in New Zealand drinking drivers

Blood alcohol concentrations (BAC) and corresponding breath alcohol concentrations (BrAC) were determined for 21,582 drivers apprehended by New Zealand police. BAC was measured using headspace gas chromatography, and BrAC was determined with Intoxilyzer 5000 or Seres Ethylometre infrared analysers. The delay (DEL) between breath testing and blood sampling ranged from 0.03 to 5.4 h. BAC/BrAC ratios were calculated before and after BAC values were corrected for DEL using 19 mg/dL/h as an estimate of the blood alcohol clearance rate. Calculations were performed for single and duplicate breath samples obtained using the Intoxilyzer (groups I-1 and I-2) and Seres devices (groups S-1 and S-2). Before correction for DEL, BAC/BrAC ratios for groups I-1, I-2, S-1, and S-2 were (mean+/-SD) 2320+/-260, 2180+/-242, 2330+/-276, and 2250+/-259, respectively. After BAC values were adjusted for DEL, BAC/BrAC ratios for these groups were (mean+/-SD) 2510+/-256, 2370+/-240, 2520+/-280, and 2440+/-260, respectively. Our results indicate that in New Zealand the mean BAC/BrAC ratio is 19-26% higher than the ratio of the respective legal limits (2000).     

Financial Liberalization and Stock Price Behaviour in Asian Emerging Markets

This paper exhibits tests of the random walk hypothesis and market efficiency for seven Asian emerging markets as a result of the influence of financial market integration. Random walk properties of equity prices influence the return dynamic and determine the trade strategies of investors. To examine the stochastic properties of local index returns and to test the hypothesis that stock market prices follow a random walk, the single variance ratio tests of Lo and MacKinlay, as well as the multiple variance ratio test of Chow and Denning are employed. The multiple statistical comparison of variance ratios is based on the Studentized Maximum Modulus distribution with control of the joint-test’s size. The weak-form market efficiency is also tested directly, using a nonparametric runs test. These tests are particularly useful for investigating stock prices the returns of which are frequently not distributed normally. Documented evidence shows that, from the perspective of local investors, weekly stock prices in major Asian emerging markets do not follow a random walk in the pre-liberalization period. However, in the post-liberalization period the weak-form efficiency hypothesis is generally adopted at the 5% level except for the smaller stock markets of Indonesia and Thailand. These empirical findings suggest that financial integration affects the return predictability in such a way that domestic investors might not be able to develop trading strategies allowing them to earn abnormal returns.     

ISFG: Recommendations on biostatistics in paternity testing

The Paternity Testing Commission (PTC) of the International Society for Forensic Genetics has taken up the task of establishing the biostatistical recommendations in accordance with the ISO 17025 standards and a previous set of ISFG recommendations specific to the genetic investigations in paternity cases. In the initial set, the PTC recommended that biostatistical evaluations of paternity are based on a likelihood ratio principle – yielding the paternity index, PI. Here, we have made five supplementary biostatistical recommendations. The first recommendation clarifies and defines basic concepts of genetic hypotheses and calculation concerns needed to produce valid PIs. The second and third recommendations address issues associated with population genetics (allele probabilities, Y-chromosome markers, mtDNA, and population substructuring) and special circumstances (deficiency/reconstruction and immigration cases), respectively. The fourth recommendation considers strategies regarding genetic evidence against paternity. The fifth recommendation covers necessary documentation, reporting details and assumptions underlying calculations. The PTC strongly suggests that these recommendations should be adopted by all laboratories involved in paternity testing as the basis for their biostatistical analysis.     

海洛因来源鉴定的新方法

毒品来源的鉴定是指对毒品样品中包含的来源信息进行提取拜分析,这有助于打击毒品犯罪.海洛因是危害我国的主要毒品,它的来源鉴定更引起人们的关注.本文介绍了国际上研究海洛因来源的三种方法,即研究海洛因样品中的各种有机杂质及其相对比例;研究海洛因样品中的痕量无机元素;研究海洛因及吗啡的稳定同位素相对比值.第三种方法能够反映样品的地域性特点,因而在来源鉴定方面有突出的优势.气相色谱-燃烧-同位素比值质谱法是同位素比值测定方法中用于海洛因来源鉴定的最佳手段.这一技术还可用于其他微量物证(如炸药、药品、油品等)的来源鉴别,因而在法庭科学领域内显示了广阔的应用前景.     

Short term impact of Tribulus terrestris intake on doping control analysis of endogenous steroids

Tribulus terrestris is a nutritional supplement highly debated regarding its physiological and actual effects on the organism. The main claimed effect is an increase of testosterone anabolic and androgenic action through the activation of endogenous testosterone production. Even if this biological pathway is not entirely proven, T. terrestris is regularly used by athletes. Recently, the analysis of two female urine samples by GC/C/IRMS (gas chromatography/combustion/isotope-ratio-mass-spectrometry) conclusively revealed the administration of exogenous testosterone or its precursors, even if the testosterone glucuronide/epitestosterone glucuronide (T/E) ratio and steroid marker concentrations were below the cut-off values defined by World Anti-Doping Agency (WADA). To argue against this adverse analytical finding, the athletes recognized having used T. terrestris in their diet. In order to test this hypothesis, two female volunteers ingested 500 mg of T. terrestris, three times a day and for two consecutive days. All spot urines were collected during 48 h after the first intake. The (13)C/(12)C ratio of ketosteroids was determined by GC/C/IRMS, the T/E ratio and DHEA concentrations were measured by GC/MS and LH concentrations by radioimmunoassay. None of these parameters revealed a significant variation or increased above the WADA cut-off limits. Hence, the short-term treatment with T. terrestris showed no impact on the endogenous testosterone metabolism of the two subjects.     

夫妻一方对他方自杀而“见死不救”之刑事责任新探——从“宋福祥故意杀人案”之判决理由谈起

"罪刑法定原则"与"罪刑相适应原则"已经成为我国刑法的基本原则。"宋福祥故意杀人案"之判决理由欠缺合理性与合法性,夫妻一方对他方自杀而"见死不救"的不应当承担刑事责任。在刑事审判中,法官应"以事实为根据,以法律为准绳",以作出正当的个案裁判为己任,在审判中真正做到符合"罪刑法定原则"与"罪刑相适应原则",才能切实保障公民的合法权益,维护社会的和谐稳定,也才能真正实现依法治国。