Three conditions under which experiments and observational studies produce comparable causal estimates: New findings from within‐study comparisons

This paper analyzes 12 recent within‐study comparisons contrasting causal estimates from a randomized experiment with those from an observational study sharing the same treatment group. The aim is to test whether different causal estimates result when a counterfactual group is formed, either with or without random assignment, and when statistical adjustments for selection are made in the group from which random assignment is absent. We identify three studies comparing experiments and regression‐discontinuity (RD) studies. They produce quite comparable causal estimates at points around the RD cutoff. We identify three other studies where the quasi‐experiment involves careful intact group matching on the pretest. Despite the logical possibility of hidden bias in this instance, all three cases also reproduce their experimental estimates, especially if the match is geographically local. We then identify two studies where the treatment and nonrandomized comparison groups manifestly differ at pretest but where the selection process into treatment is completely or very plausibly known. Here too, experimental results are recreated. Two of the remaining studies result in correspondent experimental and nonexperimental results under some circumstances but not others, while two others produce different experimental and nonexperimental estimates, though in each case the observational study was poorly designed and analyzed. Such evidence is more promising than what was achieved in past within‐study comparisons, most involving job training. Reasons for this difference are discussed. © 2008 by the Association for Public Policy Analysis and Management.     

利用aroA基因建立鸡传染性鼻炎PCR诊断方法

利用aroA基因设计了1对引物,分别对10株标准副鸡嗜血杆菌(HPG)菌株、14株分离的HPG菌株进行PCR扩增,结果均得到了与预期大小一致的片段,而对10株非HPG菌株和3株病毒进行扩增则无相应片段产生;该PCR能检测出10个菌细胞.与常规PCR方法相比,aroA-PCR的敏感性更高.     

Gender and Evidence in Family Law Reform: A Case Study of Quantification and Anecdote in Framing and Legitimising the ‘Problems’ with Child Support in Australia

Despite claims of ‘evidence based policy’, the place of empirical evidence in family law reform is ambiguous. There is ongoing socio-legal analysis of the differential value and uses of quantitative data and anecdote in detailing women’s experiences and advocating for change. In this paper, we engage with these issues through a focus on how data were constructed in a key government report, Every Picture Tells a Story, which was used to officially define the problem and outline recommendations in the controversial 2006-08 reform of the Australian Child Support Scheme. Our discussion focuses on two questions: what legitimacy is accorded to different kinds of evidence in family law reform processes?; and, how is this legitimacy gendered? We applied feminist critical discourse analysis to the type, source and claims of the data included in the child support chapter of the report. Our findings indicate that both quantitative data and anecdote were used to privilege fathers’ financial interests and autonomy; in contrast, women’s voices and interests were marginalised. Thus, we argue the legitimacy of data is ascribed through its relationship to the gendered definition of the ‘problems’ of child support, rather than the type of data per se.     

Family negativity and delinquent behavior in adolescence: a predictive multivariate latent growth analysis

ABSTRACT

The current study had three aims: (1) to explore whether there is over-time change in adolescent delinquency and negativity in the parent–adolescent, sibling and marital relationships during adolescence; (2) to examine the interactions of negativity across subsystems; and (3) to examine whether levels and changes in adolescent delinquency are predicted by levels and changes in negativity in all family subsystems. Data of 497 families participating in the RADAR-young study were used. Ratings of all family members were used to measure negativity in family relationships, and adolescent self-report was used for delinquency. Multivariate latent growth curve models showed over-time increases in mother-adolescent negativity and over-time decreases in sibling negativity, as well as significant individual differences in these changes. Second, evidence for both social contagion and compensatory processes in family negativity was found. Third, initial levels of parent–adolescent negativity were related to initial levels but not over-time changes of adolescent delinquency, whereas initial levels of sibling negativity were related to over-time changes but not initial levels of adolescent delinquency. Finally, increases in parent–adolescent negativity were related to faster increases in adolescent delinquency, and decreases in sibling negativity were related to slower increases in adolescent delinquency. Implications of these results are discussed.