Demand for general practitioner and internist services.

Demand equations for general-practitioner and internist visits were estimated from 1970 CHAS-NORC survey data on health-service utilization and expenditure. Because a large proportion of respondents reported zero visits, observations were grouped according to cross-classified independent variables and regression analyses were performed using group means as data. The results showed significant differences between demand equations for general-practitioner visits and those for internist visits. Of potential importance was an apparent substitution of internists for general practitioners as ability to pay (income or insurance coverage) increased. Own-price elasticities were low for both general practitioners and internists but were even lower for the latter (0.1 to 0.02) than the former (0.2 to 0.3). The demand for services of the two specialties also differed with respect to disability days, age, sex, residence, and race.