Official websites use. Share sensitive information only on official, secure websites. Email: D. Wolke warwick. Participant drop-out occurs in all longitudinal studies, and if systematic, may lead to selection biases and erroneous conclusions being drawn from a study. Teacher reports of disruptive behaviour among currently participating, previously participating and never participating children aged 8 years in the ALSPAC longitudinal study were collected. Data on family factors were obtained in pregnancy.
Simulations were conducted to explain the impact of selective drop-out on the strength of prediction. Drop out from the ALSPAC cohort was systematic and children who dropped out were more likely to suffer from disruptive behaviour disorder. Systematic participant drop-out according to the family variables, however, did not alter the association between family factors obtained in pregnancy and disruptive behaviour disorder at 8 years of age.
Cohort studies are prone to selective drop-out and are likely to underestimate the prevalence of psychiatric disorder. This empirical study and the simulations confirm that the validity of regression models is only marginally affected despite range restrictions after selective drop-out. Prospective studies provide one of the strongest methodologies for studying aetiological mechanisms, 1 but are vulnerable to selection biases as a result of losses to follow-up.
Participant losses can be random 2 or systematically related to social or biological characteristics of the participants that may or may not be associated with the outcome of interest. We investigated the impact of selective participant drop-out using a prospective study and conducted a series of simulations to explain the empirical findings. The Avon Longitudinal Study of Parents And Children ALSPAC collected data about disruptive behaviour problems from teachers on all children attending participating schools within the Avon area at 7 years 9 months allowing us to examine the following questions.
Finally, we conducted simulations to explain the impact of selective drop-out on the strength of prediction if drop-out, predictor and criterion variables are correlated to varying degrees. The Avon Longitudinal Study of Parents And Children 5 is a population-based study which investigates a wide range of environmental, genetic and psychosocial influences on the health and development of children and their parents.
