This study describes a method for incorporating external estimates of intraclass correlation to improve the precision for the analysis of an existing group-randomized trial. The authors use a random-effects meta-analytic approach to pool the information across studies, which takes into account any interstudy heterogeneity that may exist. This…

This article presents a synopsis of each of seven presentations given at a conference on design and analysis in community trial studies. Papers identify problems with community trials and discuss strengths and weaknesses associated with design and analysis strategies. Areas of consensus are summarized. (SLD)

Studied the analytic problems associated with a design in which one identifiable group is allocated to each treatment condition and members of these groups are measured to assess the intervention. Results from a simulation study underscore the analytic problems associated with these quasi-experimental or group-randomized designs. (SLD)

Strategies to avoid the penalties of extra variation described by J. Cornfield and reduced degrees of freedom in community-level trials were compared in Monte Carlo simulations. The three conditions necessary to ensure nominal Type I and Type II error rates are detailed. (SLD)

A Monte Carlo study compared performance of linear and logistic mixed-model analyses of simulated community trials having specific event rates, intraclass correlations, and degrees of freedom. Results indicate that in studies with adequate denominator degrees of freedom, the researcher may use either method of analysis, with certain cautions. (SLD)