Age at menarche based on recall information.

Censored likelihood methods which use recalled dates yield accurate estimates of the age at menarche in an urban population of black adolescent girls. The mean age at menarche is 12.44 (SE 0.08) years for a sample of 272 black adolescents in Philadelphia, PA. The methodology we describe is more efficient than logit or probit methods, which are not designed to utilize recall information. Alternative methods which use recall are biased if subject memory is influenced by length of time since menarche. Our methods also provide information on the nature of subject recall that may be useful in further analysis.