Some design issues in a community intervention trial.

We present statistical considerations for the design of a 20-community randomized trial. The community intervention aims at multiple cancer prevention health behaviors including reducing dietary fat, increasing fruit and vegetable intake, smoking cessation, and increasing colorectal cancer screening. To better measure the overall impact of the intervention, individual endpoints as well as a global test of multiple endpoints are used. The statistical power analysis takes into account the heterogeneity between communities, the correlation between health behaviors over time, and the correlation between multiple endpoints. The study is being conducted in a relatively confined geographic area. Several measures have been taken to account for potential contamination. These include collecting information in baseline and follow-up surveys on intervention dose and conducting surveys in three similar communities in another part of the state.