Heterogeneity: GAW Group 15.

This paper summarizes the contributions to Group 15 of Genetic Analysis Workshop (GAW) 14, which focused on methods for dealing with heterogeneity in linkage and association analysis. A variety of methods were employed, ranging from manipulation of the phenotype and/or identification of endophenotypes prior to analysis, to statistical methods allowing for heterogeneity in the analysis of simple dichotomous phenotypes as provided with the data. Overall, it was difficult to draw broad conclusions from these applications.