Setting capitation payments in markets for health services.

Health maintenance organizations (HMO's) are paid a capitated amount for enrolled Medicare beneficiaries that is 95 percent of what these enrollees would be expected to cost in the fee-for-service sector. However, it appears that HMO enrollees are less costly than other Medicare beneficiaries. With a simulation model, we demonstrate that with a 95-percent pricing rule, any significant degree of biased selection leads to increased cost to the payer, even when HMO's are cost effective compared with the fee-for-service sector. Optimal pricing percentages from the point of view of cost minimization are considerably less than 95 percent.