Table 5.

Cross-classification of subjects by quartiles of the frequency of dairy and fish product intake estimated with a food frequency questionnaire (FFQ) and the µg/mL of plasma phospholipid pentadecanoic acid, EPA, and DHA (n=102^a)

	Correctly classified (%)	Correct plus adjacent quartiles (%)	Grossly misclassifiedb (%)
Dairy intake and pentadecanoic acid
Cheese	38.2	73.5	4.9
Total milk	30.3	64.5	14.7
Total milk/yoghurt	27.4	65.6	11.8
Total fat dairy	31.4	75.6	3.9
Total dairy	30.4	70.7	5.9
Fish intake and EPA
Total oily fish	31.4	71.6	5.8
Other fish	25.5	67.7	5.9
Total fish	29.4	69.4	5.9
Cod liver oil	38.1	72.4	5.9
Cod liver oil/total oily fish	42.1	81.3	3.9
Cod liver oil/total fish	41.1	82.2	3.9
Fish intake and DHA
Total oily fish	33.3	76.4	4.0
Other fish	22.6	60.8	8.8
Total fish	32.3	74.5	6.9
Cod liver oil	41.1	76.4	3.9
Cod liver oil/total oily fish	42.1	80.4	3.9
Cod liver oil/total fish	42.2	82.4	3.9

^aEight observations were considered as outliers and excluded from the analysis.

^bClassified into opposite quartiles.