Development and validation of a food frequency questionnaire for Japanese athletes (FFQJA)

Table 4 Comparison of energy and nutrient intakes from dietary records and food frequency questionnaires for Japanese athletes based on joint classification by quintiles

Nutrient intake	Joint classification by quintile (%)				Weighted kappa statistics
	Same category	Adjacent category	± 2 categories	± 3 categories	Kappa statistics	95% confidence interval
Energy	49	30	18	4	0.38	0.22–0.54
Protein	36	43	13	9	0.23	0.07–0.40
Fat	32	43	17	9	0.17	0.01–0.33
Carbohydrate	39	38	18	6	0.25	0.09–0.42
Calcium	43	42	14	3	0.38	0.23–0.52
Iron (Fe)	32	53	9	6	0.27	0.13–0.42
Retinol	49	31	18	3	0.40	0.24–0.56
Vitamin B₁	30	35	32	4	0.11	−0.06–0.27
Vitamin B₂	43	42	14	3	0.38	0.23–0.52
Vitamin C	36	48	13	4	0.32	0.17–0.46
Dietary fiber	43	42	12	5	0.36	0.21–0.51

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