2.2. Study design

This study was a population-based follow-up study with 2-wave surveys conducted on retirees in Taiwan during 2015–2019. The purpose of the study was to examine four factors, two life stressors and two types of social engagement, on the changes in loneliness when controlling for other critical covariates. Thus, the outcome variable was the changes in feelings of loneliness, whereas the study variables were all assessed at baseline in order to present the temporal relationship.