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

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

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 agreementa Weighted kappa % correctly classified into same quintile % classified within one quintile % grossly misclassified Strength of agreementa
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
  1. Kappa statistics undertaken on unadjusted (crude) data.
  2. * denotes p-value < 0.05; ** denotes p-value < 0.01
  3. a Landis and Koch classification (Landis and Koch 1977)
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