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Table 6 Kappa statistics for food-frequency questionnaires (FFQ1 and FFQ2) for reproducibility

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

Energy & Nutrients

FFQ1 vs FFQ2

(n = 101)

 

Weighted kappa

% correctly classified into same quintile

% classified within one quintile

% grossly misclassified

Strength of agreementa

Energy (kJ)

0.42 **

30

69

1

Moderate

Protein (g)

0.48 **

30

79

4

Moderate

Fat (g)

0.47 **

34

71

1

Moderate

Sat Fat (g)

0.43 **

32

72

3

Moderate

Poly Fat (g)

0.44 **

37

69

4

Moderate

Mono Fat (g)

0.45 **

29

74

2

Moderate

Carbohydrate (g)

0.37 **

30

67

3

Fair

Sugars (g)

0.36 **

23

68

4

Fair

Fibre (g)

0.44 **

34

73

5

Moderate

Thiamin (mg)

0.41 **

34

66

4

Moderate

Riboflavin (mg)

0.41 **

30

68

4

Moderate

Niacin (mg)

0.54 **

36

77

2

Moderate

Niacin equiv (mg)

0.53 **

39

77

3

Moderate

Vitamin C (mg)

0.42 **

32

67

0

Moderate

Folate (μg)

0.41 **

36

72

4

Moderate

Vitamin A (μg)

0.38 **

36

63

3

Fair

Retinol (μg)

0.47 **

36

72

2

Moderate

Betacarotene (μg)

0.49 **

33

70

1

Moderate

Magnesium (mg)

0.41 **

28

70

4

Moderate

Calcium (mg)

0.45 **

27

68

3

Moderate

Iron (mg)

0.41 **

28

66

3

Moderate

Zinc (mg)

0.49 **

32

75

3

Moderate

  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)