OBSERVER ERROR AND BIRTH-WEIGHT - DIGIT PREFERENCE IN RECORDING

We investigated the presence of digit preference in the recording of b irthweight by a retrospective analysis of an official dataset of birth registrations. All births occurring in the Province of Saskatchewan i n Canada from 1981 to 1991, but excluding 1988, were considered for th is analysis. Preference for the terminal digit 0 increased progressive ly with increasing birthweight over the whole range of birthweights. C orrection for digit preference led to an increase of 1.8% in the numbe r of low birthweight babies and a concomitant increase of 0.1% in the actual incidence of low birthweight. Epidemiological applications of b irthweight should take into account the observer error caused by digit preference.