HMOs' and PPOs' role in health benefits.
D003625:Data Collection; D006264:Health Benefit Plans, Employee / Q000706:statistics & numerical data*; D006279:Health Maintenance Organizations / Q000706:statistics & numerical data*; D007348:Insurance, Health / Q000706:statistics & numerical data*; D008329:Managed Care Programs / Q000706:statistics & numerical data*; D011243:Preferred Provider Organizations / Q000706:statistics & numerical data*; D014481:United States