Table 3.

Mediation analyses: Expenditure as mediator of socioeconomic inequalities in healthiness of choices. Estimates of indirect and direct effects represent the differences in the purchase of each food category associated with decreasing occupational social class.

		Percent energy from less-healthy foods/beverages	Percent energy from fruit and vegetablesa
Without supermarket choice group	Indirect effectb (a × b)	2.71⁎(2.32, 3.07)	− 0.10⁎(− 0.12, − 0.09)
Direct effect (c′)	1.61⁎(0.60, 2.61)	− 0.18⁎(− 0.24, − 0.13)
Proportion of total effect mediated	63%	36%
With supermarket choice group	Indirect effectb (a′ × b)	2.14⁎(1.81, 2.49)	− 0.08⁎(− 0.09, − 0.06)
Direct effect (c′)	1.87⁎(0.86, 2.88)	− 0.18⁎(− 0.24, − 0.13)
Proportion of total effect mediated	53%	31%

Bootstrapped standard errors; bias-corrected confidence intervals in parentheses.

Occupational social class was used as an indicator of socioeconomic status, and modelled using dummy variables, running separate analyses for Higher vs. Middle occupational social class and Higher vs. Lower occupational social class (with Higher occupational social class as the reference group in both analyses). These estimates were then aggregated to give the total indirect and direct effects of expenditure as a mediator of occupational social class in healthiness of choices. Regressions controlled for age, gender and ethnic group of main shopper; number of adults in household, number of children in household, and region of residence. Less-healthy foods and beverages were defined by FSA Nutrient Profile (28) scores for individual products (foods scoring 4 or more, and beverages 1 or more).

^aPercent energy from fruit and vegetable and expenditure were log-transformed in analyses.

^bSee Fig. 1 for pathways a, a′, b and c′.

^⁎p < 0.05.

Data from UK, 2010.