Impulsivity and sensation seeking were assessed at only Waves 1 and 8–11, thus data at intervening waves were not available. The two domains of personality were taken from the Impulsivity (8 item) and Sensation Seeking (11 item) subscales of the Zuckerman-Kuhlmen Personality Questionnaire (Zuckerman, Kuhlman, Joireman, Teta, & Kraft, 1993). Factor analytic work has demonstrated that there are distinct facets of impulsivity including: urgency, lack of planning, and lack of perseverance (Stautz & Cooper, 2013; Whiteside & Lynam, 2001). The items provided on the Zuckerman-Kuhlman inventory most closely resemble the lack of planning facet rather than the broader construct of impulsivity. As such, scores on this measure will be referred to as “ZK Impulsivity” to avoid the implication that this measure provides comprehensive coverage of impulsivity domains. Examples of items for each scale include: ZK Impulsivity, “I usually think about what I am going to do before doing it,” (reverse scored) and Sensation Seeking, “I like doing things just for the thrill of it.” Each item was scored dichotomously and reversed scored where appropriate, with respondents endorsing either 0 = false or 1 = true.
