The importance of panel, or longitudinal, survey data for analyzing subjective wellbeing, and especially its dynamics, is increasingly recognized. Analyses of such data, however, have to deal with two potential problems: (1) non-random attrition; and (2) panel conditioning. The former is a much researched topic. In contrast, panel conditioning has received much less attention from the research community. In this analysis, longitudinal survey data collected from members of a large national probability sample of households are used to examine whether self-reported measures of psychological well-being exhibit any tendency to change over time in a way that might reflect panel conditioning. Regression models are estimated that control for all time invariant influences as well as a set of time-varying influences. We find very little evidence that mean life satisfaction scores vary with length of time in the panel, especially once non-random attrition is controlled for. In contrast, scores on a measure of mental health do vary with time, and surprisingly men and women exhibit opposing patterns. For men, scores decline over time (though the estimates are not statistically robust), whereas for women the effects are both large and rise with time. Further, for both outcome measures there is a clear narrowing in the dispersion of reported scores over the first few waves of participation. The findings have implications for empirical research employing longitudinal data. Copyright Springer Science+Business Media Dordrecht 2014
