title: Adjusting for selection biases in referral populations.
mesh_terms: D000328:Adult; D002769:Cholelithiasis / Q000150:complications; D005706:Gallbladder Neoplasms / Q000209:etiology; D006417:Hematuria / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D011336:Probability; D012017:Referral and Consultation; D012107:Research Design; D012306:Risk; D013959:Thyroid Diseases / Q000150:complications; D013964:Thyroid Neoplasms / Q000209:etiology; D001749:Urinary Bladder Neoplasms / Q000209:etiology