An analysis of the British National Morbidity Survey (based on 53 practices for 1 year) revealed the nature of the underlying distribution of episodes and consultations. This project will test the applicability of this distribution to similar information collected in Virginia practices. (11 practices in the first year and 23 practices thereafter). The denominator for episode/consulting rates will be estimated by three independent methods: a) by a sample survey of the families of those living in the practice, b) against the estimated number of 'active' patients; i.e., families reporting at least one illness in the last two years, and c) by census estimates adjusted for the loss of patients to other doctors. This will confirm the efficiency of the back projection method in estimating denominators. Previously, this method will be checked on English data for which denominators are known. A knowledge of the underlying distribution of episodes and consultations in family medicine will lead to theoretical relationships between episode rates and episode rates per person consulting and between consulting rates and consulting rates per person consulting. It should therefore be possible to compare work load and referred morbidity rates in different practices even though the denominator is unknown in each case. Subsequent reseach will identify factors associated with the patterns of demand in differing practices and the demand distributions for sub-groups. After adjustment for the differences in the morbidity and threshold of different communities, practice performance may be evaluated. This information will be translated into manpower needs in primary care. Ultimately, this research should provide a method by which a physician can audit his practice and tools by which performance and health care needs may be evaluated.