Search

The lack of consistent presentation of results in published studies on the association between a quantitative explanatory variable and a quantitative dependent variable has been a long-term issue in evaluating the reported findings. Studies are analyzed and reported in a variety of ways. The main purpose of this review is to illustrate the procedures in summarizing and synthesizing research results from multivariate models with a quantitative outcome variable. The review summarizes the application of the standardized regression coefficient as an effect size index in the context of meta-analysis and describe how it can be estimated and converted from data presented in original research articles. An example of synthesis is provided using research articles on the association between childhood body mass index and carotid intima-media thickness in adult life. Finally, the paper shares practical recommendations for meta-analysts wanting to use the standardized regression coefficient in pooling findings. [ABSTRACT FROM AUTHOR]

Abstract: There is reasonably strong evidence linking reduced secondary sex ratio (proportion of males) and environmental exposures. Polychlorinated biphenyls (PCBs) are persistent contaminants of the environment and several studies have reported an association of PCBs with birth outcomes. A decrease in the male/female sex ratio at birth has been reported in some, but not all studies. The aim of this systematic review was to summarize and pool the research findings about the influence of PCBs on sex ratio. Several article databases and reference lists of identified articles were searched. Studies reporting the proportion of boys and girls born to individuals who were exposed to high PCB concentrations were included. The primary outcome measure was the proportion of males in groups exposed to high or low levels of PCBs. Studies with both direct and indirect surrogate PCB measurements were included. The search and selection resulted in 15 eligible studies on the association between the sex ratio and parental PCB exposures. Analyses of the high exposure groups showed that the sex ratio was not significantly altered from the historical reference range in 13 of the 15 articles. The majority of the exposure studies reported also internal comparisons between high and low PCB exposure levels. The pooled 95% confidence interval estimate for the difference in high and low maternal exposure with direct PCB measure was – 0.048 with 95% CI of (−0.121, 0.026). There was no strong or moderate indication that parental exposure to PCBs alters the sex ratio of the children. [Copyright &y& Elsevier]

There has been a greatly increased interest in statistical methods in the psychiatric research and its applications over the past few decades, in parallel with advances in computers and statistical software. This review aims to describe the main topics related to statistical methods in psychopharmacology, namely nature of statistics in medicine, problems in data analysis, statistical modelling, developments in statistical technology, statistical reporting and meta-analysis. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]