Guzick D S
Health Serv Res. 1978 Winter;13(4):351-68.
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.
根据1970年美国全国民意研究中心（NORC）的健康服务利用与支出调查数据，估算了全科医生和内科医生就诊的需求方程。由于很大一部分受访者报告就诊次数为零，因此根据交叉分类的自变量对观测值进行分组，并以组均值作为数据进行回归分析。结果显示，全科医生就诊的需求方程与内科医生就诊的需求方程存在显著差异。随着支付能力（收入或保险覆盖范围）的提高，内科医生明显替代了全科医生，这一点可能很重要。全科医生和内科医生的自身价格弹性都较低，但后者（0.1至0.02）比前者（0.2至0.3）更低。这两个专科服务的需求在残疾天数、年龄、性别、居住地点和种族方面也存在差异。
