Reproducibility and comparative validity of a food frequency questionnaire for Australian children and adolescents

Table 5 Kappa statistics for food-frequency questionnaires (FFQ1 and FFQ2) and assisted food records (FRs) for comparative validity

Energy & Nutrients	Average FFQ1 and FFQ2 vs FRs (n = 101)					FFQ2 vs FRs (n = 113)
	Weighted kappa	% correctly classified into same quintile	% classified within one quintile	% grossly misclassified	Strength of agreement^a	Weighted kappa	% correctly classified into same quintile	% classified within one quintile	% grossly misclassified	Strength of agreement^a
Energy (kJ)	0.27 **	30	58	3	Fair	0.14	22	56	4	Slight
Protein (g)	0.22 *	27	57	5	Fair	0.13	20	56	6	Slight
Fat (g)	0.25 *	26	59	3	Fair	0.21 *	21	58	3	Fair
Sat Fat (g)	0.36 **	33	64	3	Fair	0.31 **	27	62	3	Fair
Poly Fat (g)	0.20 *	32	61	5	Slight	0.11	28	58	6	Slight
Mono Fat (g)	0.21 *	27	60	5	Fair	0.20 *	22	58	4	Slight
Carbohydrate (g)	0.23 *	23	56	2	Fair	0.21 *	27	56	4	Fair
Sugars (g)	0.30 **	30	61	4	Fair	0.24 *	31	58	4	Fair
Fibre (g)	0.40 **	37	68	1	Fair	0.25 **	21	60	2	Fair
Thiamin (mg)	0.29 **	28	55	1	Fair	0.21 *	27	59	4	Fair
Riboflavin (mg)	0.37 **	27	66	1	Fair	0.22 *	21	58	1	Fair
Niacin (mg)	0.27 **	29	63	4	Fair	0.13	26	55	5	Slight
Niacin equiv (mg)	0.33 **	23	63	4	Fair	0.16	24	57	6	Slight
Vitamin C (mg)	0.23 *	25	64	5	Fair	0.27 **	30	61	3	Fair
Folate (μg)	0.41 **	29	60	0	Moderate	0.22 *	19	58	2	Fair
Vitamin A (μg)	0.24 *	34	56	3	Fair	0.14	21	56	7	Slight
Retinol (μg)	0.12	18	52	12	Slight	0.09	20	52	4	Slight
Betacarotene (μg)	0.24 *	27	64	4	Fair	0.27 **	28	65	6	Fair
Magnesium (mg)	0.35 **	29	64	2	Fair	0.26 **	27	61	5	Fair
Calcium (mg)	0.35 **	32	71	5	Fair	0.31 **	29	65	5	Fair
Iron (mg)	0.45 **	27	70	1	Moderate	0.36 **	27	64	2	Fair
Zinc (mg)	0.24 *	23	56	1	Fair	0.17 *	19	51	4	Slight

ISSN: 1479-5868