Partnership effects in general practice: identification of clustering using intra-class correlation coefficients.

Although most United Kingdom general practitioners (GPs) work together in a shared professional arrangement termed 'partnership', little is known about the nature of such partnerships. We report the results of a survey of 61 general practice partners in 15 group practices and their attitudes to prescribing and managerial issues related to participation in a commissioning group. Intra-class correlation coefficients (ICCs) were used to explore how these individually held attitudes clustered within groups. The low ICCs found for attitudes relating to prescribing issues suggested that GPs acted individually in this respect, while, in contrast, responses to managerial questions clustered strongly in partnerships, implying that managerial attitudes were more likely to be shared within partnerships. The ICC statistic is a useful tool for exploring homogeneity and heterogeneity within general practice partnerships.