The Impact of Access Regulation on Health Insurance Market Structure. Health Maintenance Organizations


Alpha Center obtained photocopies of every HMO filing in 1995, and coded and entered selected fields from these filings into an electronic database. To obtain 1996 and 1997 information, we purchased from InterStudy its standard HMO financial database for 1996 and 1997, enhanced with selected additional premium and medical loss figures by line of business. Due to the enhancement of the standard database, these data are proprietary to Alpha Center. From these data, we identified 638 HMOs operating in 1996 and 671 HMOs operating in 1997.