Table 2.

Concurrent criterion validation of dietary indices

	n	HEI	MDS	HFD-index
Men vs women	443:4604	56.4:60.4***	4.2:4.6***	0.2:0.19⊥
Over 60s vs under 60s	2543:2504	59.8:60.3⊥	4.5:4.6**	0.2:0.2⊥
Smokers vs non-smokers	317:2909	55.9:61***	4.1:4.7***	0.16:0.21***

Three dietary indices, the Healthy Eating Index (HEI), the Mediterranean Diet Score (MDS) and the Healthy Food Diversity index (HFD-index) were assessed for their ability to predict difference of diet of smokers vs non-smokers, over 60s vs under 60s, and men vs women via two sample t test (HFD-index via Wilcoxon rank sum). Difference in means is displayed for each grouping, with significance thresholds indicated by: **p < 0.01, ***p < 0.001, ⊥ = non-significant. Results of tests are indicated in Additional file 1: Table S2