Individuals' perceptions of their own level of cognitive ability are expressed through self-estimates. They play an important role in a person's self-concept because they facilitate an understanding of how one's own abilities relate to those of others. People evaluate their own and other persons' abilities all the time, but self-estimates are also used in formal settings, such as, for instance, career counseling. We examine the relationship between self-estimated and psychometrically measured cognitive ability by conducting a random-effects, multilevel meta-analysis including a total of 154 effect sizes reported in 41 published studies. Moderator variables are specified in a mixed-effects model both at the level of the individual effect size and at the study level. The overall relationship is estimated at r ϭ .33. There is significant heterogeneity at both levels (i.e., the true effect sizes vary within and between studies), and the results of the moderator analysis show that the validity of self-estimates is especially enhanced when relative scales with clearly specified comparison groups are used and when numerical ability is assessed rather than general cognitive ability. The assessment of less frequently considered dimensions of cognitive ability (e.g., reasoning speed) significantly decreases the magnitude of the relationship. From a theoretical perspective, Festinger's (1954) theory of social comparison and Lecky's (1945) theory of selfconsistency receive empirical support. For practitioners, the assessment of self-estimates appears to provide diagnostic information about a person's self-concept that goes beyond a simple "test-and-tell" approach. This information is potentially relevant for career counselors, personnel recruiters, and teachers.

The stress-buffering hypothesis postulates that physical activity and exercise can buffer the negative effects of (academic) stress on health. It still remains an open question whether students, who regularly engage in physical activity and exercise within their academic examination period, can successfully diminish these negative effects. Sixty-four subjects participated in this study and completed a total of five surveys, with T1 at the end of the semester break (baseline) and T2–T5 being presented every Friday in the last 4 weeks of the semester (examination period). They were asked to answer questions about their activity level, sleep quality, well-being and affect. Hierarchical linear models showed significant dependencies on time for all dependent measures. The expansion of the model for exercise also showed significant main effects of this predictor on well-being and positive affect (PA) and negative affect. Moreover, significant interactions with time for sleep quality and PA were found. Results suggest that physical activity and exercise in the academic examination period may be able to buffer the negative effects of stress on health-related outcomes. Therefore, activity levels should be maintained in times of high stress to prevent negative effects on sleep, well-being and affect in students.

Abstract. During the past 20 years, Situational Judgment Tests (SJTs) have developed into a viable tool in personnel selection. Despite their growing popularity, research examining the extent of measurement error is widely lacking. Using reliability generalization, the aim of this article was twofold: (1) establish an estimate for an average coefficient alpha of SJT scores across studies and (2) examine the influence of essential SJT features and selected study variables on score reliability. To handle potential dependent observations a three-level hierarchical linear model was used. The results indicate that the reliability of SJT scores is typically rather low and below recommended levels for high-stakes applications. Additionally, both SJT and study characteristics affect score reliability. Implications for practitioners and researchers are provided to guide an appropriate use of SJTs and to initiate future research.

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