An empirical analysis of HMO market share.
D000368:Aged; D001291:Attitude of Health Personnel; D003365:Costs and Cost Analysis; D003710:Demography; D006123:Group Practice / Q000458:organization & administration; D006264:Health Benefit Plans, Employee / Q000191:economics / Q000458:organization & administration; D006279:Health Maintenance Organizations / Q000191:economics / Q000458:organization & administration; D006301:Health Services Needs and Demand; D006801:Humans; D008389:Marketing of Health Services / Q000191:economics; D008875:Middle Aged; D008962:Models, Theoretical; D010820:Physicians / Q000523:psychology; D012959:Socioeconomic Factors; D013223:Statistics as Topic; D014481:United States