'Staying the distance': Characteristics of women who do not contisnue in a longitudinal study of pregnancy-related moods

Abstract

Many studies suffer from threats to the study design that arise through random and non-random loss of respondents and the effects on the data that is able to be collected. In quasi-experimental research, participant response problems relate particularly to the three categories of refusal to enter the study although eligible, eventual non-response in spite of previous agreement to participate, and, in longitudinal designs with repeated measures, attrition or 'drop-out' occurring during later stages. The results hat are eventually reported are limited to the findings from only those who remained, from whom the data were actually obtained. In the many studies carried out to identify pregnancy-r..