On data and methods in investigations on parental-age effects Comments on a paper by J. D. Erickson

Abstract

An analysis of the NIS [National Cleft Lip and Palate Intelligence Services] data used by Erickson has rvealed that it contains too few Down''s syndrome cases with older fathers. Thus the data is less suited for an investigation of a possible paternal age effect. The statistical tests used by Erickson have low power, so that they are unable to detect a moderate paternal-age effect. Discussions on paternal-age effects and similar problems should be based on high-quality data. The investigation is better based on a small high-quality material than on a large one with serious under-ascertainment. The missing observations nearly always have common characteristics which may cause serious bias of relevant kinds.