ABSTRACT
This chapter explains to what extent general practitioners (GPs) working in the same practice behave alike and to what extent GP practices differ from one another. It also explains whether visibility of a doctor's clinical behaviour and the use of shared resources influence decisions on prescription, referrals, diagnostics, treatment, and advice. The chapter presents two coefficients of correlation: the intra-class correlation (ICC), measured in two different ways. The ICC is a measure of homogeneity within practices, or, in other words, the degree of resemblance within the same practice. The chapter finds that clustering of variation within practices depends on the clinical activity studied. GPs working within the same practice differed more from colleagues in other practices than from their colleagues in the same practice, for activities like treatment and diagnostics performed in the GP's practice. There is significant variation both between and within practices for prescription, and diagnostics performed in the GP's practice.
