Who enrolls in a prepaid group practice: the Columbia experience.
D001294:Attitude to Health; D005191:Family Characteristics; D006123:Group Practice; D006268:Health Facilities / Q000706:statistics & numerical data; D006306:Health Surveys; D007354:Insurance, Major Medical / Q000706:statistics & numerical data*; D008396:Maryland; D010548:Personal Health Services / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D014505:Urban Population