This paper deals with the question of selectivity of missing data on income questions in large panel surveys due to item-non-response and with imputation as one alternative strategy to cope with this issue. In contrast to cross-section surveys, the imputation of missing values in panel data can...

Like many medical studies, the Berlin Aging Study II (BASE-II) is based on a non-random "gconvenience sample" of self-recruited participants. To study processes of selectivity in BASE-II, we used a questionnaire to compare BASE-II with a large, representative reference study, the German...