The different subsamples used different versions of Cloninger's personality scales (see Table 2 - Tridimensional Personality Questionnaire (TPQ short version, see Cloninger et al. 1991; Heath et al. 1994) and Temperament and Character Inventory (TCI, Cloninger et al. 1993). To get homogenous phenotypes, in this study we only included the 54 items of the revised short version of the TPQ (as used in the QIMR sample); all these items were also incorporated in the other questionnaires. This yielded 18 Harm Avoidance, 19 Novelty Seeking, 12 Reward Dependence, and 5 Persistence items. Internal consistency of the scales of this short version of the TPQ were acceptable and comparable with those reported for the full TPQ scales and the short-term test-retest reliability of the scales was good (see Table 1 in Keller et al. 2005 for these statistics on the QIMR subsample). These items and scales are the same as used in Keller et al (2005) to estimate genetic and environmental variance components from twin-family data, except that they analysed one item as contributing to the Reward Dependence scale while we assigned it to the Novelty Seeking scale in accordance with the scales' revision (Cloninger 1994).
