Attrition and generalizability in longitudinal studies: findings from a 15-year population-based study and a Monte Carlo simulation study

摘要

BackgroundAttrition is one of the major methodological problems in longitudinal studies. It can deteriorate generalizability of findings if participants who stay in a study differ from those who drop out. The aim of this study was to examine the degree to which attrition leads to biased estimates of means of variables and associations between them.