Table 6

Agreement of quartile assignment between the short FFQ and vitamin D, measured as 25(OH)D in serum.

Quartile

Same quartile

Adjacent quartile

Misclassified

1 (n = 12)

5

5 (above)

2 (above)

2 (n = 17)

4

9 (4 above, 5 below)

4 (above)

3 (n = 12)

3

7 (4 above, 2 below)

1 (below)

4 (n = 12)

4

4 (below)

5 (below)

Total number (n = 53)

16

25

12

%

30

47

23

Dahl et al. Nutrition Journal 2011 10:127   doi:10.1186/1475-2891-10-127