A re-evaluation of random-effects meta-analysis

Summary.  Meta-analysis in the presence of unexplained heterogeneity is frequently undertaken by using a random-effects model, in which the effects underlying different studies are assumed to be drawn from a normal distribution. Here we discuss the justification and interpretation of such models, by addressing in turn the aims of estimation, prediction and hypothesis testing. A particular issue that we consider is the distinction between inference on the mean of the random-effects distribution and inference on the whole distribution. We suggest that random-effects meta-analyses as currently conducted often fail to provide the key results, and we investigate the extent to which distribution-free, classical and Bayesian approaches can provide satisfactory methods. We conclude that the Bayesian approach has the advantage of naturally allowing for full uncertainty, especially for prediction. However, it is not without problems, including computational intensity and sensitivity to a priori judgements. We propose a simple prediction interval for classical meta-analysis and offer extensions to standard practice of Bayesian meta-analysis, making use of an example of studies of 'set shifting' ability in people with eating disorders.     

Corporate Quotas and Symbolic Politics in Advanced Democracies

ABSTRACT

This article identifies trends in the adoption and implementation of quotas for corporate boards, an underresearched topic in political science. Corporate quotas—like legislative quotas—constitute the “fast track” to gender equality but appear more commonly in advanced democracies. These corporate quotas fall into three categories: laws covering all companies; laws covering state-owned companies only; and nonbinding (voluntary) measures in corporate governance codes. Despite on-paper differences, these corporate quotas are largely toothless. First generation corporate quotas, like first generation legislative quotas, operate symbolically. By raising the specter of stringent legislation in the long run, corporate quotas induce firms into voluntary compliance in the short run.     

Social Skills in Children Adopted From Socially-Emotionally Depriving Institutions

This study assessed social skills in post-institutionalized (PI) children with respect to age at adoption, age at assessment, and gender. Parent ratings of social skills (Social Skills Rating System) and behavior problems (Child Behavior Checklist) were obtained for 214 children and 127 adolescents who were adopted from socially-emotionally depriving Russian institutions. Results showed that children adopted before 18 months of age have better social skills than those adopted after this age; those assessed in childhood demonstrate better social skills than those assessed in adolescence. PI females, especially later-adopted adolescents, have particularly poor social skills. Children with poor social skills tend to have higher rates of behavior problems.     

Exercise self-regulation among older women participating in a heart disease-management intervention

Using behavioral self-regulation processes may facilitate exercise among older women with heart disease. Data from women in a heart disease-management program (n = 658, mean 73 years), was used to explore associations among exercise self-regulation components (i.e., choosing to improve exercise and observing, judging, and reacting to one's behavior) and exercise capacity. General linear models showed that choosing exercise predicted higher exercise self-regulation scores postprogram and 8 months later. In turn, these scores predicted greater improvements in exercise capacity concurrently and 8 months later. Interaction analyses revealed that the effect of self-regulation on exercise capacity was stronger among women who chose to work on exercise.     

THEORIES OF RISK: TESTING INVESTOR BEHAVIOR ON THE TAIWAN STOCK AND STOCK INDEX FUTURES MARKETS

This article considers four utility functions—concave, convex, S‐shaped, and reverse S‐shaped—to analyze the behavior of different types of investors on the Taiwan stock index and its corresponding index futures. Using stochastic dominance (SD) rules, we show that the existence of all four investor types is plausible. Risk averters prefer spot to futures, whereas risk seekers prefer futures to spot. Investors with S‐shaped utility functions prefer spot (futures) to futures (spot) when markets move upward (downward). Investors with reverse S‐shaped utility functions prefer futures (spot) to spot (futures) when markets move upward (downward). We show that both spot and futures markets can exist when only risk averters are present, but futures can dominate spot only if there is some risk‐seeking behavior. These results are robust with respect to subperiods, spot returns including dividends, and diversification. (JEL C14, G12, G15)     

Anthropological Theories of Low-Wage Work

This review assesses the use of anthropological theories in the examination of low-wage work. Due to the vast differences existing between different cultures in low-wage work, this review focuses on theories that have been applied in Western, and mainly American, contexts. There are primarily three fields from which this literature is drawn: economic anthropology, gender and race anthropology, and theories of power—the last integrates all these theories. Differences and controversies over the applicability of these theories are also highlighted. The review concludes with a conceptual map describing the interrelatedness of these theories and how they explain the realities of low-wage workers.