Heterogeneous heterogeneity by default: Testing categorical moderators in mixed-effects meta-analysis

Categorical moderators are often included in mixed-effects meta-analysis to explain heterogeneity in effect sizes. An assumption in tests of categorical moderator effects is that of a constant between-study variance across all levels of the moderator. Although it rarely receives serious thought, there can be statistical ramifications to upholding this assumption. We propose that researchers should instead default to assuming unequal between-study variances when analysing categorical moderators. To achieve this, we suggest using a mixed-effects location-scale model (MELSM) to allow group-specific estimates for the between-study variance. In two extensive simulation studies, we show that in terms of Type I error and statistical power, little is lost by using the MELSM for moderator tests, but there can be serious costs when an equal variance mixed-effects model (MEM) is used. Most notably, in scenarios with balanced sample sizes or equal between-study variance, the Type I error and power rates are nearly identical between the MEM and the MELSM. On the other hand, with imbalanced sample sizes and unequal variances, the Type I error rate under the MEM can be grossly inflated or overly conservative, whereas the MELSM does comparatively well in controlling the Type I error across the majority of cases. A notable exception where the MELSM did not clearly outperform the MEM was in the case of few studies (e.g., 5). With respect to power, the MELSM had similar or higher power than the MEM in conditions where the latter produced non-inflated Type 1 error rates. Together, our results support the idea that assuming unequal between-study variances is preferred as a default strategy when testing categorical moderators.     

Grading the ‘cultural literacy’ project

The essay examines the argument advanced by E.D. Hirsch, Jr., for instituting ‘cultural literacy’ as a fundamental priority of schools. A number of confusions and equivocations in Hirsch's reasoning are identified, and the propensity of his project to indoctrinate is exposed. Among the features of Hirsch's argument shown to be troubling are his shifting construal of ‘language’, his inconsistency about the requirements of cultural literacy, and his uncritical relation to traditional images of the American past and present. The upshot is to raise the question why Hirsch's project has elicited wide support and praise.     

Referenzsemantik in der Partnermodellierung

How can we explain that an assertion on something perceived can be understood in the same manner by somebody who cannot perceive that scene? This problem bases the interest in computational linguistics in how listener modeling could possibly be harmonized with reference semantics. Mental images substituting real perception appear as a way out. The architecture of the listener model has to be adapted to the creation and use of such pictorial data structures. Furthermore, the relation between the latter and a verbal (i. e., propositional) representation must be understood. The resulting architecture of a listener model with reference semantics can be employed to solve communicational problems from three general classes in a better way, as is demonstrated by an example implementation.     

Prospective Associations Between Peer Victimization and Internalizing Symptoms in Adolescence: The Protective Role of Hope

Youth who experience aggression at the hands of peers are at an increased risk for a variety of adjustment difficulties, including depressive and anxiety symptoms and lower self-esteem. The links between peer victimization and internalizing problems are robust, but less work has been done to identify individual-level protective factors that might mitigate these outcomes. The current study investigated whether hope served as a moderator of the prospective links from peer victimization to depressive and anxiety symptoms and self-esteem during adolescence. Participants included 166 high school students (64% female; 88% Black/African American). Youth completed self-report measures at three different time points across the Spring semester of an academic year. As predicted, hope interacted with peer victimization to predict changes in depressive and anxiety symptoms over the course of the semester. That is, for youth with low levels of hope, peer victimization predicted more stable patterns of depressive and anxiety symptoms. For adolescents with average levels of hope, however, peer victimization did not influence anxiety and depressive symptoms over time. Finally, for adolescents with high levels of hope, peer victimization predicted greater decreases in anxiety symptoms over time. Hope did not interact with peer victimization to predict self-esteem. Rather, hope uniquely predicted higher levels of self-esteem, whereas peer victimization uniquely predicted lower levels of self-esteem. The current study provides initial support for the notion that hope can serve as a protective factor among youth who are victims of peer aggression.