On the consequences of matching in retrospective studies with special regard to the calculation of relative risks.
D000328:Adult; D000367:Age Factors; D001722:Birth Order; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D012189:Retrospective Studies; D012737:Sex Factors