A general linear model for estimating effect size in the presence of publication bias

When the process of publication favors studies with smallp-values, and hence large effect estimates, combined estimates from many studies may be biased. This paper describes a model for estimation of effect size when there is selection based on one-tailedp-values. The model employs the method of maximum likelihood in the context of a mixed (fixed and random) effects general linear model for effect sizes. It offers a test for the presence of publication bias, and corrected estimates of the parameters of the linear model for effect magnitude. The model is illustrated using a well-known data set on the benefits of psychotherapy.Authors' note: The contributions of the authors are considered equal, and the order of authorship was chosen to be reverse-alphabetical.     

Sources of variability in children’s language growth

The present longitudinal study examines the role of caregiver speech in language development, especially syntactic development, using 47 parent–child pairs of diverse SES background from 14 to 46 months. We assess the diversity (variety) of words and syntactic structures produced by caregivers and children. We use lagged correlations to examine language growth and its relation to caregiver speech. Results show substantial individual differences among children, and indicate that diversity of earlier caregiver speech significantly predicts corresponding diversity in later child speech. For vocabulary, earlier child speech also predicts later caregiver speech, suggesting mutual influence. However, for syntax, earlier child speech does not significantly predict later caregiver speech, suggesting a causal flow from caregiver to child. Finally, demographic factors, notably SES, are related to language growth, and are, at least partially, mediated by differences in caregiver speech, showing the pervasive influence of caregiver speech on language growth.     

Alcohol as social lubricant.

This study examines how consuming alcohol differentially affects the communicative behavior and perceptions of high and low social self‐esteem (SSE) women as they engage in a brief interaction with a flirtatious male. Alcohol myopia theory proposes that alcohol affects behavior when it blocks a person's normal inhibitions about enacting a behavior. It was predicted that low SSE women would be more inhibited when talking to a flirtatious male than would high SSE women and, therefore administration of a social self‐esteem measure and random assignment to an alcoholic or nonalcoholic beverage condition, participants (N=50) talked with an attractive, flirtatious male confederate. Low SSE women were less anxious and self‐disclosed more when drinking than when sober, whereas high SSE women were not significantly affected by alcohol consumption. The discussion highlights the complex and often contradictory effects of alcohol consumption on social interaction.     

The varieties of speech to young children

This article examines caregiver speech to young children. The authors obtained several measures of the speech used to children during early language development (14-30 months). For all measures, they found substantial variation across individuals and subgroups. Speech patterns vary with caregiver education, and the differences are maintained over time. While there are distinct levels of complexity for different caregivers, there is a common pattern of increase across age within the range that characterizes each educational group. Thus, caregiver speech exhibits both long-standing patterns of linguistic behavior and adjustment for the interlocutor. This information about the variability of speech by individual caregivers provides a framework for systematic study of the role of input in language acquisition.     

Inclusion of theory-relevant moderators yield the same conclusions as Sedikides, Gaertner, and Vevea (2005): A meta-analytical reply to Heine, Kitayama, and Hamamura (2007)

Heine, Kitayama and Hamamura (2007) attributed the Sedikides, Gaertner and Vevea (2005) findings to the exclusion of six papers. We report a meta-analysis that includes those six papers. The Heine et al . conclusions are faulty, because of a misspecified meta-analysis that failed to consider two moderators central to the theory. First, some of their effect sizes originated from studies that did not empirically validate comparison dimensions. Inclusion of this moderator evidences pancultural self-enhancement: Westerners enhance more strongly on individualistic dimensions, Easterners on collectivistic dimensions. Second, some of their effect sizes were irrelevant to whether enhancement is correlated with dimension importance. Inclusion of this moderator evidences pancultural self-enhancement: Both Westerners and Easterners enhance on personally important dimensions. The Sedikides et al . conclusions are valid: Tactical self-enhancement is pancultural.     

Publication bias in research synthesis: sensitivity analysis using a priori weight functions

Publication bias, sometimes known as the "file-drawer problem" or "funnel-plot asymmetry," is common in empirical research. The authors review the implications of publication bias for quantitative research synthesis (meta-analysis) and describe existing techniques for detecting and correcting it. A new approach is proposed that is suitable for application to meta-analytic data sets that are too small for the application of existing methods. The model estimates parameters relevant to fixed-effects, mixed-effects or random-effects meta-analysis contingent on a hypothetical pattern of bias that is fixed independently of the data. The authors illustrate this approach for sensitivity analysis using 3 data sets adapted from a commonly cited reference work on research synthesis (H. M. Cooper & L. V. Hedges, 1994).     

Beyond the group mind: a quantitative review of the interindividual-intergroup discontinuity effect

This quantitative review of 130 comparisons of interindividual and intergroup interactions in the context of mixed-motive situations reveals that intergroup interactions are generally more competitive than interindividual interactions. The authors identify 4 moderators of this interindividual-intergroup discontinuity effect, each based on the theoretical perspective that the discontinuity effect flows from greater fear and greed in intergroup relative to interindividual interactions. Results reveal that each moderator shares a unique association with the magnitude of the discontinuity effect. The discontinuity effect is larger when (a) participants interact with an opponent whose behavior is unconstrained by the experimenter or constrained by the experimenter to be cooperative rather than constrained by the experimenter to be reciprocal, (b) group members make a group decision rather than individual decisions, (c) unconstrained communication between participants is present rather than absent, and (d) conflict of interest is severe rather than mild.     

The effects of violent video games on aggression.

Violent content video games such as Mortal Kombat and Doom have become very popular among children and adolescents, causing great concern for parents, teachers, and policy makers. This study cumulates findings across existing empirical research on the effects of violent video games to estimate overall effect size and discern important trends and moderating variables. Results suggest there is a smaller effect of violent video games on aggression than has been found with television violence on aggression. This effect is positively associated with type of game violence and negatively related to time spent playing the games. Directions for future programmatic research on video games are outlined.     

Evaluating the evidence for pancultural self-enhancement

We do not regard the better-than-average effect as 'the only acceptable measure of self-enhancement' (Heine, Kitayama, & Hamamura, 2007b). Rather, we object to meta-analytical inclusion of effects that are incapable of testing the tactical self-enhancement hypothesis. In Investigation 1 of Sedikides, Gaertner, and Vevea (2007a), 12 of the 24 effects involved attributes that were unvalidated for domain (collectivistic vs individualistic): these effects are uninformative. The 12 domain-validated effects supported the hypothesis. In Investigation 2 of Sedikides et al. (2007a), 12 of the 29 effects were deemed irrelevant. None of these effects involved a correlation between: (a) a participant's rating of self and his/her rating of another person; and (b) idiographic importance rating of the comparison attributes. These effects, then, cannot test whether the self–other comparison varies with the personal importance of the comparison attributes. The 17 relevant effects supported the hypothesis. The weight of the evidence points to the panculturality of self-enhancement.