“…A stated preferences approach solves this problem by capturing a broader array of preference-driven behaviours, and can therefore be used to estimate the causal relation between gradual retirement and a worker's age of retirement and labour supply. Concerns may arise about the external validity of retirement options in stated preference studies, especially if these retirement options do not yet exist in practice ( Kantarci and Van Soest, 2013 ). 21 However, the literature shows that stated preference estimates and estimates based on data on actual behaviour are usually quite close ( Louviere et al,20 0 0 ).…”