How close is close enough? Evaluating propensity score matching using data from a class size reduction experiment

In recent years, propensity score matching (PSM) has gained attention as a potential method for estimating the impact of public policy programs in the absence of experimental evaluations. In this study, we evaluate the usefulness of PSM for estimating the impact of a program change in an educational context (Tennessee's Student Teacher Achievement Ratio Project [Project STAR]). Because Tennessee's Project STAR experiment involved an effective random assignment procedure, the experimental results from this policy intervention can be used as a benchmark, to which we compare the impact estimates produced using propensity score matching methods. We use several different methods to assess these nonexperimental estimates of the impact of the program. We try to determine “how close is close enough,” putting greatest emphasis on the question: Would the nonexperimental estimate have led to the wrong decision when compared to the experimental estimate of the program? We find that propensity score methods perform poorly with respect to measuring the impact of a reduction in class size on achievement test scores. We conclude that further research is needed before policymakers rely on PSM as an evaluation tool. © 2007 by the Association for Public Policy Analysis and Management     

美国模范刑法典导论

美国法学会1962年通过的《模范刑法典》在美国刑法法典化的历史中发挥了最重要的作用。自颁布至今,该法典一直是美国刑法典改革的主导力量,也是美国刑法学研究的催化剂。该法典内容上包括总则、具体犯罪的规定、处遇和矫正、矫正组织四编,总体上采用了“原则性实用主义”的进路。该法典的创新之处体现在:全面的总则、分析性的结构、充分界定犯罪、使用限定的术语、法典条款的解释体系、犯罪体系,以及某些具体规则的创新,如犯罪要件、不完整犯罪和同谋犯、正当事由、免责事由等。     

Mismatch distribution analysis of Y-STR haplotypes as a tool for the evaluation of identity-by-state proportions and significance of matches--the European picture

We suggest the use of the mismatch distribution methodology as an easy way to estimate the distance between all pairs of haplotypes present in a sample. This approach allows the evaluation of the proportion of pairs of Y-STR haplotypes that are prone to become identical by state (IBS), in one generation, by recurrent mutation, a statistic of major importance in the forensic field. The mismatch approach presents some advantages alternatively to the empirical one, since it is not necessary to have simultaneous information on STRs and SNPs, and it allows the evaluation of IBS also within-haplogroups. The estimation of IBS at an European scale showed that there is a high population substructuring for this parameter, increasing from southern-central European countries towards west and north, in accordance to what was found for Y-biallelic markers. This result seems to imply a more careful use of large databases for matching evaluation, even in the absence of population structure for general Y-STR diversity. Furthermore, mismatch distribution can be used to measure the distance between a particular haplotype and all the haplotypes in a sample. When applied to the most frequent haplotypes in Europe it revealed that the opportunity for IBS is not directly related to the frequency of a haplotype, but highly dependent on the proportion of neighbouring haplotypes--so, that reporting on the haplotype frequency for evaluating the significance of a match can be misleading.     

Early Adolescent Social and Overt Aggression: Examining the Roles of Social Anxiety and Maternal Psychological Control

This study examined the factors contributing to the self-reported use of social and overt aggression among 745 10–14-year-old European American and Latino adolescents. Hierarchical multiple regression analyses showed that dispositional social evaluative anxiety was uniquely positively associated with boys’ and girls’ social aggression and negatively associated with boys’ overt aggression. Maternal psychological control was positively associated with overt aggression for all boys, but with social aggression only for Latino boys. Although maternal psychological control also was associated with girls’ use of overt aggression, this effect was stronger among older than among younger females. The relationship between maternal psychological control and girls’ social aggression was mediated by social evaluative anxiety. Implications for elevated levels of social evaluative anxiety are discussed within a social cognitive theory perspective and for maternal psychological control within a social learning theory perspective.Received Ph.D. in Developmental Psychology from Michigan State University. Research interests include the interacting influences of individual differences and contextual factors on child and adolescent aggression.Research interests include examining the familial and peer systemic influences on child and adolescent aggression, individual differences influencing child and adolescent aggression, and interventions to reduce bullying behavior in peer groups.Received Ph.D. in School Psychology from Mississippi State University. Research interests include developing interventions in the classroom for disruptive behaviors, increasing prosocial behaviors, and decreasing aggression.     

Anthropological measurement of lower limb and foot bones using multi-detector computed tomography

Anthropological examination of defleshed bones is the gold standard for osteological measurement in forensic practice. However, multi-detector computed tomography (MDCT) offers the opportunity of three-dimensional imaging of skeletal elements, allowing measurement of bones in any plane without defleshing. We present our experiences of the examination of 15 human lower limbs in different states of decomposition using MDCT. We present our method of imaging and radiological measurement of the bones including sex assessment. The radiological measurements were undertaken by three professional groups--anthropology, radiology, and forensic pathology--both at the site of scanning and at a remote site. The results were compared to anthropological oestological assessment of the defleshed bones. We discuss the limitations of this technique and the potential applications of our observations. We introduce the concept of remote radiological anthropological measurement of bones, so-called tele-anthro-radiology and the role that this could play in providing the facility for standardization of protocols, international peer review and quality assurance schemes.     

Gasoline on hands: preliminary study on collection and persistence

The identification of an arsonist remains one of the most difficult challenges a fire investigation has to face. Seeking and detection of traces of gasoline could provide a valuable information to link a suspect with an arson scene where gasoline was used to set-up the fire. In this perspective, a first study was undertaken to evaluate a simple, fast and efficient method for collecting gasoline from hands, and to assess its persistence over time. Four collection means were tested: PVC, PE and Latex gloves, as well as humidified filter paper. A statistical assessment of the results indicates that Latex and PVC gloves worn for about 20 min, as well as paper filter rubbed on hands, allow an efficient collection of gasoline applied to hands. Due to ease of manipulation and to a reduced amount of volatile compounds detected from the matrix, PVC gloves were selected for the second set of experiments. The evaluation of the persistence of gasoline on hands was then carried out using two initial quantities (500 and 1000 microl). Collection was made with PVC gloves after 0, 30 min, 1, 2 and 4h, on different volunteers. The results show a common tendency of massive evaporation of gasoline during the first 30 min: a continued but non-linear decrease was observed along different time intervals. The results of this preliminary study are in agreement with other previous researches conducted on the detection of flammable liquid residues on clothes, shoes and skin.