The Medicare Payment Advisory Commission as found that geographic variation in Medicare spending is substantial. But the Commission told Congress recently that much of the variation could be explained by local differences in the cost of providing care and in the health status of beneficiaries, as well as by extra payments, authorized by Congress, for hospitals that train doctors or treat large numbers of low-income patients. The new government data are adding fuel to a raging debate over what Congress should do to reduce geographic disparities in Medicare spending.