Fig. 3
Causal pathway diagram with standardized estimates illustrating the total effects of adolescent SEP on diet quality in early adulthood. Parental education (A), and area-level disadvantage (B), are used as indicators of SEP to examine the mediating role of adolescent dietary determinants in associations between SEP in adolescence and diet quality in early adulthood based on Capability, Opportunity, Motivation and Behaviour (COM-B) model. The endogenous variables (dependent) are diet quality and COM. COM represent potential mediators at baseline (latent variables) on the pathway between SEP at baseline (measured variable) and diet quality at T3 (measured variable). In this COM model, Capability was a latent variable designed to represent food-related activities and skills, Opportunity was a latent variable designed to represent availability of fruit and vegetables in the home, and Motivation was a latent variable designed to represent confidence that can eat healthily (self-efficacy). The mediated effects of SEP on diet quality through Capabilities, Opportunities and Motivations (indirect effect – represented by dashed line) were estimated by multiplying the direct effects of SEP on each mediator (paths a1 − 3) by the direct effect of each mediator on diet quality (paths b1 − 3). The individual mediating effect of Capability, Opportunity and Motivations, as well as the joint mediating effects (Opportunity -> Capability -> Motivation) on associations between SEP and diet quality were estimated. The association between SEP and diet quality, i.e., total effect, is represented by path c. Significant pathways are indicated as * for p < 0.05 and ** for p < 0.01