Table 2

Measures of reproducibility for single questions about consumption frequency in the test and retest food frequency questionnaire (FFQ)

Agreement, %

Misclassification, %

Symmetry of misclassification, %

Kappa





Food item (response options)

n

Total

Never/rarelya

± 1 Categ.b

± 2 Categ.b

Extr.c

Retest<Test

Retest>Test

Difference

Simple

Weighted


Potatoes (7)

1452

62

1

25

9

0.0

21

17

4

0.48

0.61

Carrots (7)

1406

43

1

42

11

0.0

35

22

13

0.30

0.54

Salad (7)

1169

41

3

41

12

0.0

22

37

-15

0.28

0.52

Swede (7)

1134

49

7

38

8

0.0

31

20

11

0.32

0.52

"Other vegetables" (7)

865

34

8

35

18

0.5

34

32

2

0.20

0.37

Oranges (7)

1107

39

5

34

20

0.1

50

12

38

0.25

0.47

"Other fruits" (7)

978

39

4

34

17

0.2

29

33

-4

0.25

0.42

Whole milk (6)

710

85

78

11

3

0.1

8

6

2

0.52

0.61

Meat, reindeer (6)

1339

86

75

11

1

0.6

8

6

2

0.58

0.57

Roast (beef, pork, lamb) (5)

1280

54

13

37

7

0.1

26

20

6

0.33

0.42

Meat, chops (5)

1301

62

10

35

4

0.0

15

24

-9

0.42

0.52

"Other meat dishes" (5)

921

40

11

41

15

0.2

31

28

3

0.21

0.32

Cod/coalfish/haddock/pollack (6)

1362

48

2

41

9

0.0

29

22

7

0.32

0.51

Salmon/trout (6)

1225

53

5

39

7

0.0

22

25

-3

0.35

0.48

Fish liver (5)

1229

78

43

18

3

0.2

12

10

2

0.68

0.77

Shellfish (4)

1374

70

35

27

2

0.1

13

17

-4

0.54

0.62

Beer (7)

1005

63

41

29

6

0.0

14

23

-9

0.46

0.61

Wine (7)

1137

46

13

40

13

0.0

19

35

-16

0.34

0.60

Chocolate (6)

1402

57

18

35

6

0.0

26

17

9

0.42

0.57

Cod liver oil capsules, winter (5)

156

76

3

13

3

5.1

9

15

-6

0.33

0.45

Cod liver oil capsules, rest of year (5)

130

69

15

12

4

11.5

15

16

-1

0.44

0.53


aLowest response category in the FFQ, bCategories: ± 1 or ± 2 from the line of agreement in the contingency table

cExtremes: test-retest responses in the lowest and highest categories

Parr et al. Nutrition Journal 2006 5:4   doi:10.1186/1475-2891-5-4

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