PT - JOURNAL ARTICLE AU - Zyzanski, Stephen J. AU - Flocke, Susan A. AU - Dickinson, L. Miriam TI - On the Nature and Analysis of Clustered Data AID - 10.1370/afm.197 DP - 2004 May 01 TA - The Annals of Family Medicine PG - 199--200 VI - 2 IP - 3 4099 - http://www.annfammed.org/content/2/3/199.short 4100 - http://www.annfammed.org/content/2/3/199.full SO - Ann Fam Med2004 May 01; 2