Analysis of site-specific data in dental studies.

Much attention has been given recently to issues in the statistical analysis of site data arising from clinical trials in periodontics. As pointed out by Imrey (1986) and Fleiss et al. (1987), it is unreasonable to expect sites within the same patient to respond independently, and thus conventional statistical methods are not directly applicable. In this paper we develop a procedure for comparing the percentage of sites showing a given characteristic across two or more groups of patients that accounts for this lack of independence. The procedure is a straightforward extension of the standard Pearson chi-square test. Two examples are given.