Lateral preferences for hand clasping and arm folding are associated with handedness in two large-sample latent variable analyses.

Hand clasping (HC) and arm folding (AF) are bilateral limb postures which are subject to lateral preferences. Previous research suggested that left HC and left AF are "canonical" among European populations, i.e., generally preferred by right-handers. However, evidence on the associations of handedness with HC and AF to date is sparse and inconsistent, with studies mostly relying on relatively small sample sizes and arbitrary classifications of handedness. Utilizing latent class analysis for handedness classification, we present data from two large and independent middle-European samples, a discovery (n = 7,658) and replication (n = 5,062) sample. Our results indicate that right HC, not left HC, is overall preferred and that right-handedness is associated with right HC/left AF, and left- and mixed-handedness with left HC/right AF. Moreover, lateral preferences increased with age, and men had a higher preference of right HC, independent of handedness. We discuss our findings with regard to the generalizability of previous results.

Finding your way out of the forest without a trail of bread crumbs: development and evaluation of two novel displays of forest plots.

Research has shown that forest plots are a gold standard in the visualization of meta-analytic results. However, research on the general interpretation of forest plots and the role of researchers' meta-analysis experience and field of study is still unavailable. Additionally, the traditional display of effect sizes, confidence intervals, and weights have repeatedly been criticized. The current work presents an online statistical cognition experiment in which a total of 279 researchers with experience in meta-analysis from 36 countries evaluated conventional forest plots and two novel versions of forest plots, namely, thick forest plots and rainforest plots. The results indicate certain biases in the interpretation of forest plots, especially with regard to heterogeneity, the distribution of weights, and the theoretical concept of confidence intervals. Although the two novel displays (thick forest plots and rainforest plots) are associated with slightly longer viewing times, they are at least as well-suited and esthetically and perceptively pleasing as the conventional displays while facilitating the correct and exhaustive interpretation of the meta-analytic information. Furthermore, it is advisable to combine conventional forest plots with distribution information of the individual effects, make confidence lines more visually striking, and to display a background grid in the graph.

Ethnicity moderates the association between 5-HTTLPR and national suicide rates.

The association between ethnicity, national suicide rates, and the functional serotonin transporter gene polymorphism (5-HTTLPR), under consideration of the role of economic indicators, national alcohol intake, and national happiness scores was analyzed with an ecologic analysis. Data on allelic frequencies of the short (s) allele from 38 countries from over 100,000 healthy screened or general population individuals were analyzed with multiple regression models. Allele frequency varied widely both within and across ethnicities and an ethnicity-based interaction between national suicide rates and 5-HTTLPR allele frequency was revealed with the s allele acting as protective factor in Caucasian and as a risk factor in non-Caucasian populations. This interaction effect underlines the importance of ethnicity as a moderating factor in the genetics of suicide.

Less is less: a systematic review of graph use in meta-analyses.

Graphs are an essential part of scientific communication. Complex datasets, of which meta-analyses are textbook examples, benefit the most from visualization. Although a number of graph options for meta-analyses exist, the extent to which these are used was hitherto unclear. A systematic review on graph use in meta-analyses in three disciplines (medicine, psychology, and business) and nine journals was conducted. Interdisciplinary differences, which are mirrored in the respective journals, were revealed, that is, graph use correlates with external factors rather than methodological considerations. There was only limited variation in graph types (with forest plots as the most important representatives), and diagnostic plots were very rare. Although an increase in graph use over time could be observed, it is unlikely that this phenomenon is specific to meta-analyses. There is a gaping discrepancy between available graphic methods and their application in meta-analyses. This may be rooted in a number of factors, namely, (i) insufficient dissemination of new developments, (ii) unsatisfactory implementation in software packages, and (iii) minor attention on graphics in meta-analysis reporting guidelines. Using visualization methods to their full capacity is a further step in using meta-analysis to its full potential.

Genetic association studies between SNPs and suicidal behavior: a meta-analytical field synopsis.

The large number of published meta-analyses on the associations between single-nucleotide polymorphisms (SNPs) and suicidal behavior mirrors the enormous research interest in this topic. Although meta-analytic evidence is abundant and certain patterns are apparent, those have not been integrated into a general framework as of yet. In a systematic review, genetic association studies between SNPs and suicidal behavior were identified. Previously published meta-analyses for eight SNPs were updated and the results of the different meta-analyses were compared. Meta-analyses for 15 SNPs, which had not been subjected to meta-analysis before, were conducted. The present meta-analytical field synopsis showed five major similarities between new and published analyses: 1) Summary effect sizes were small and rarely statistically significant, 2) heterogeneity between studies was often substantial, 3) there were no time trends, 4) effects were easily swayed and were largely dependent on individual studies, and 5) publication bias does not play a role in this field of research. Meta-analytic data show once more that major contributions of single genes are unlikely. However, association studies and corresponding meta-analyses have been an important and necessary stepping stone in the development of modern and more complex approaches in the genetics of suicidal behavior.

Development of a scale to assess knowledge about suicide postvention using item response theory.

Knowledge about suicide postvention (KSPV) is an important distal outcome in the evaluation of suicide prevention programs that focus on the bereaved. However, most scales are specifically tailored to the evaluation study in question and psychometric properties are often unsatisfactory. Therefore, we developed the KSPV scale. Scale properties were investigated with Rasch trees, a newly developed method in the framework of item response theory. Additionally, we provide cues for convergent validity. In summary, the scale shows satisfactory properties for assessing KSPV and could be used to evaluate suicide postvention programs more effectively.