enquête (1) échantillonnage (1) plan (1) perte (1) revenu (1) santé (1) épidémiologie (1) index (1) Epidemiology (1) Dental care (1) Teenagers (1) Ci (Chinese poetry) (1) Teeth (1) Sampling (1) Regression analysis (1) Orthodontics (1) Manufacturers' agents (1) Malocclusion (1) Income (1) Health (1) Ethnicity (1) Epidemiology (1) Education (1) Dental care (1) Commission merchants (1) Brown (1) Black (1) Back (1) Schooling (1) Sampling (1)