When selecting motivation-related constructs to include in our study, we used expectancy-value theory (Eccles et al., 1983) because it was developed "to help explain gender differences in mathematics expectancies and values and how these influence boys and girls' choices of mathematics courses and majors" (Wigfield, Tonks, & Klauda, 2009, p. 56).
We therefore classified studies as selected or not selected by motivation to quit.
Four mechanisms were selected: cognition, motivation, social cognition (communication with others), and metacognition (self-evaluation skills and help-seeking ability).
Populations in which participants were not selected by motivation to quit were less likely to create this spurious difference between quitters and continuing smokers.
Clearly, it will be more effective for physicians to offer assistance to all smokers, not only to those selected by motivation [ 38].
In a subgroup analysis we compared the 16 studies in which participants were all attempting to quit with the 10 studies in which participants were not selected by motivation to quit.
We have selected the Protection Motivation Theory for this study.
Thus, the participants were not self selected by their motivation to improve their diagnostic skills.
In the present study herds were conveniently selected based upon motivation, as was done in previous studies to guarantee an adequate follow up and to minimize data loss [ 3, 8, 10, 13, 32- 35].
In contrast, it is likely that these strains were never selected for higher motivation to approach humans, given that domesticated and wild strains did not show clear differences in terms of the durations of 'heading toward' and 'contacting' a human hand in the active tame test.
a) Selected measures of self competency taken from the Raine cohort [ 45], including Cowen's Self Efficacy [ 46] and Adolescent Self Perception Profile [ 47]. b) 12 selected items from Motivation and Engagement; Enjoyment of School, Academic Buoyancy and Class Participation scales [ 48, 49].
