Virtual Tool Mark Generation for Efficient Striation Analysis,

This study introduces a tool mark analysis approach based upon 3D scans of screwdriver tip and marked plate surfaces at the micrometer scale from an optical microscope. An open‐source 3D graphics software package is utilized to simulate the marking process as the projection of the tip's geometry in the direction of tool travel. The edge of this projection becomes a virtual tool mark that is compared to cross‐sections of the marked plate geometry using the statistical likelihood algorithm introduced by Chumbley et al. In a study with both sides of six screwdriver tips and 34 corresponding marks, the method distinguished known matches from known nonmatches with zero false‐positive matches and two false‐negative matches. For matches, it could predict the correct marking angle within ±5–10°. Individual comparisons could be made in seconds on a desktop computer, suggesting that the method could save time for examiners.     

Distortion in Fingerprints: A Statistical Investigation using Shape Measurement Tools

Friction ridge impression appearance can be affected due to the type of surface touched and pressure exerted during deposition. Understanding the magnitude of alterations, regions affected, and systematic/detectable changes occurring would provide useful information. Geometric morphometric techniques were used to statistically characterize these changes. One hundred and fourteen prints were obtained from a single volunteer and impressed with heavy, normal, and light pressure on computer paper, soft gloss paper, 10‐print card stock, and retabs. Six hundred prints from 10 volunteers were rolled with heavy, normal, and light pressure on soft gloss paper and 10‐print card stock. Results indicate that while different substrates/pressure levels produced small systematic changes in fingerprints, the changes were small in magnitude: roughly the width of one ridge. There were no detectable changes in the degree of random variability of prints associated with either pressure or substrate. In conclusion, the prints transferred reliably regardless of pressure or substrate     

Media consumption: Using social attitudes to segment society – a typology of a South African sample

Abstract

In this, the first of a two-article series, an attitudinal typology was developed for use in a subsequent study of media consumption and psychographic variables. The current study used multivariate statistics to identify types of individuals who are similar to one another, across multiple measures of attitudes towards social issues. Agglomerative hierarchical cluster analysis of data from 11 533 South Africans, aged 16 years and older, revealed six distinct types based on the component ‘attitudinal variables’. The types were labelled Contemporaries, Conventionals, Unconcerneds, Self-involveds, Old-schoolers and Confidents. Preliminary analysis of available demographic variables revealed significant differences for age, population group, gender, work status, home language, SAARF Lifestages and SAARF Universal Living Standard Measure (SU-LSM®) for the six types. The typology illustrates the possibility of empirical identification of distinct attitudinal types of a South African sample. Methodological limitations and recommendations for further research are discussed.     

The 1881 census in the Russian Baltic provinces: An inventory and an assessment

The 1881 census of the Russian Baltic provinces of Livland, Estland, and Kurland was the first modern-type systematic population enumeration in the Baltic area. It had been preceded by enumerations of other kinds—land cadastres that included aggregate population counts (during Swedish control of the area) in the 17th century, and fiscal revisions (during Russian control of the area) that did list residents by name but did not follow any principles of modern census-taking. The Baltic German politico-economic elite, which controlled public affairs in the Baltic provinces, decided to carry out a census of a modern kind, and produced the 1881 count. Although initially the initiative was coordinated by the statistical specialists of the three provinces, the publication of results was decentralized, resulting in a series of volumes that supplied different tables for each province. The article analyzes the contents of the census, some of its shortcomings, as well as its strengths.     

岗位实训量化管理模式构建与实践——安徽省2011年省级示范实习实训中心项目研究内容

岗位实训是指公安院校的校外实训。岗位实训量化管理模式是根据实训计划内容和要求,对学生在公安机关基层工作中所承担工作任务进行分解统计,将工作内容转化为一定数据,及时、客观反映实训过程、状态和效果,并以此为依据实施实训管理的方式。实训中,对学生从事的工作进行统计量化,形成反映实训实时动态的量化数据,以此作为管理基础,可增强管理的科学性和有效性。由于工作量统计内容多、过程复杂,为确保量化管理模式有效运行,必须建立和完善实训量化机制,在统计项目、统计人员、统计过程、统计职责等关键环节上要有明确规定,以保证统计结果的真实性和教学管理的有效性。实践证明,将量化统计方法应用岗位实训中,构建实训量化管理模式,着力解决管理难题,能为岗位实训教学实现精细化发展奠定坚实基础。     

The Determinants of Gender Differences in Income in Trinidad and Tobago

The present study employs 1993 Continuous Sample Survey of the Population data for Trinidad and Tobago to investigate the causes of gender income differentials. The findings suggest that such differentials are not well explained by differences in levels of human capital and other measured factors valued by the labour market. This result is robust to the disaggregation of the data into African, Indian and Other ethnic groups thereby raising the possibility of gender discrimination. African and Indian women's incomes would increase by over 20 per cent with the returns to the measured factors of their male, ethnic counterparts. Women would benefit from having men's industry distribution of jobs, but not men's occupational distribution. African women appear to be significantly more disadvantaged relative to their male counterparts than are Indian or Other women.     

Comparing village characteristics derived from rapid appraisals and household surveys: A tale from northern Mali.

This paper investigates whether inferences drawn about a population are sensitive to the manner by which those data are obtained. It compares information obtained using participatory appraisal techniques with a survey of households randomly drawn from a locally administered census that had been carefully revised. The community map tends to include households that do not, in fact, reside in the enumerated locality. By contrast, the revised official census is slightly more likely to exclude households who actually lived in the surveyed area. Controlling for the survey technique, we find that the revised official census produces higher estimates of average household size and wealth but lower estimates of total village size or wealth, than the community map. Pairwise comparison of the survey techniques, holding the households constant, shows that the community map leads, on average, to higher estimates of household size and lower estimates of wealth.     

Quantifying Uncertainty in Estimations of the Total Weight of Drugs in Groups of Complex Matrices: Using the Welch–Satterthwaite Equation

In this paper, a method is described to quantify estimations of the total amount of drugs in groups of seized items, including quantification of the precision. Previous work on this topic was based on the assumptions of normally distributed measurements and grouping of items with a common relative standard deviation. In practice, these assumptions are often violated, for example, for data with point masses at 0, or if certain items in a group have a very high standard deviation. The method described in this paper is based on work by Welch and Satterthwaite and does not assume constant relative standard deviations. Case examples are described for which the method is applied, and simulation studies are carried out for which both methods are applied. In the cases, both methods perform reasonably well. If the assumption of common relative standard deviations clearly does not apply, it is advised to use the method described.     

The Development and Application of Random Match Probabilities to Firearm and Toolmark Identification

The field of firearms and toolmark analysis has encountered deep scrutiny of late, stemming from a handful of voices, primarily in the law and statistical communities. While strong scrutiny is a healthy and necessary part of any scientific endeavor, much of the current criticism leveled at firearm and toolmark analysis is, at best, misinformed and, at worst, punditry. One of the most persistent criticisms stems from the view that as the field lacks quantified random match probability data (or at least a firm statistical model) with which to calculate the probability of a false match, all expert testimony concerning firearm and toolmark identification or source attribution is unreliable and should be ruled inadmissible. However, this critique does not stem from the hard work of actually obtaining data and performing the scientific research required to support or reject current findings in the literature. Although there are sound reasons (described herein) why there is currently no unifying probabilistic model for the comparison of striated and impressed toolmarks as there is in the field of forensic DNA profiling, much statistical research has been, and continues to be, done to aid the criminal justice system. This research has thus far shown that error rate estimates for the field are very low, especially when compared to other forms of judicial error. The first purpose of this paper is to point out the logical fallacies in the arguments of a small group of pundits, who advocate a particular viewpoint but cloak it as fact and research. The second purpose is to give a balanced review of the literature regarding random match probability models and statistical applications that have been carried out in forensic firearm and toolmark analysis.