Matching in retrospective studies; sampling via the dependent variable.
D000063:Accidents, Traffic; D000328:Adult; D000367:Age Factors; D002648:Child; D002769:Cholelithiasis / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D009017:Morbidity; D009026:Mortality; D009203:Myocardial Infarction / Q000453:epidemiology; D009519:New York City; D010915:Pityriasis / Q000453:epidemiology; D011051:Poliomyelitis / Q000453:epidemiology; D012189:Retrospective Studies; D013223:Statistics as Topic; D013548:Sweden; D014611:Vaccination