To examine the extent to which physician's sex explains variation in the activity level and service intensity of a cohort of physicians in each of five medical fields after other sources of variation are taken into account.
Data from the Ontario Ministry of Health (MOH) and the CMA were analysed by means of multivariate regression techniques for panel data.
Ontario.
A total of 137 dermatologists, 974 general internists, 330 pediatricians and 941 psychiatrists and a random sample of 2771 family physicians and general practitioners who met the eligibility criteria. Physicians were eligible if they billed the MOH for at least three quarters in 1983, did not bill as a medical laboratory director, provided direct patient care, did not have an alternative funding arrangement with the MOH, remained in the same specialty throughout the study period (1983-90) and billed from an Ontario address.
Three measures of total activity level (annual number of services provided, annual fee-for-service billings and annual mean number of patients seen per quarter) and one measure of service intensity (annual mean number of services per patient per quarter).
Although several variables (e.g., full-time work status, age, type of practice and recent practice move) influenced the four measures examined, physician's sex contributed significantly to explaining variation in activity in 70% of the regression equations. The women provided 33.0% fewere services per year than the men in family and general practice (p