Economic class and use of physician services.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D004522:Educational Status; D005006:Ethnicity; D005191:Family Characteristics; D005260:Female; D005102:Health Expenditures; D006801:Humans; D007182:Income; D008297:Male; D008396:Maryland; D008484:Medicaid; D006278:Medicare; D008875:Middle Aged; D010820:Physicians / Q000706:statistics & numerical data*; D012494:Sampling Studies; D012737:Sex Factors; D012959:Socioeconomic Factors