Nutritional self-efficacy
We measured nutritional self-efficacy with the 16-item Cardiac
Diet Self-Efficacy (CDSE) scale (Hickey et al. 1992),
which measures self-efficacy for healthy dietary behaviour.
Self-efficacy is a concept developed from social learning theory
(Bandura 1977a), where behaviour is determined by
interactions between personal and environmental variables
(Bandura 1977b). Responses to questions on the CDSE are
scored from 1 (very little)–5 (quite a lot) (Hickey et al.
1992). Item scores are summed to obtain a total score;
higher scores indicate greater confidence in one’s ability to
follow a healthy diet.
Health locus of control
We assessed HLC using the 18-item multidimensional HLC
(MHLC) scale (Wallston et al. 1978), which measures individuals’
beliefs about the factors controlling their health.
The MHLC has three 6-item subscales: (1) internal HLC
(IHLC); (2) powerful HCL (PHLC); and (3) chance HLC
(CHLC). The IHLC measures the degree to which individuals
believe that their health depends on their own behaviour.
The PHLC measures how much individuals believe that their
health status results from powerful others’ actions. The
CHLC measures the extent to which individuals perceive
that their health is influenced by chance, fate or luck.
Respondents to the MHLC rate items on a 6-point Likert
scale from 1 (strongly disagree)–6 (strongly agree). Subscales
are scored by summing items. Higher IHLC, PHLC and
CHLC scores indicate stronger beliefs in one’s own, powerful
others’, or chance control over one’s health respectively.