Table 4

Over- and under-reporting in quantitative MWS variables by quintiles of corresponding NSHD data

1st quintile

2nd quintile

3rd quintile

4th quintile

5th quintile


Variable (units)

N

mean error (SD)*

N

mean error (SD)*

N

mean error (SD)*

N

mean error (SD)*

N

mean error (SD)*

P


Self-reported at recruitment in the MWS

Height (cm)

91

0.6 (2.2)

93

1.0 (2.0)

86

0.8 (3.8)

89

0.7 (2.8)

90

1.1 (2.3)

0.645

Weight (kg)

92

-0.2 (3.0)

88

-1.3 (2.8)

90

-2.3 (3.8)

87

-2.6 (4.2)

86

-4.9 (5.4)

<0.001

Body mass index (kg/m2)

90

-0.3 (1.2)

90

-0.5 (1.8)

88

-0.9 (1.8)

87

-1.5 (1.6)

82

-2.5 (2.6)

<0.001

Age at menarche ‡ (yr)

12

1.4 (1.4)

57

0.3 (0.9)

117

0.1 (1.2)

155

0.1 (1.1)

53

-0.2 (1.2)

<0.001

Age at menopause (yr)

33

-0.1 (2.4)

26

-0.5 (2.4)

31

0.1 (1.0)

27

-0.3 (0.8)

17

-0.8 (1.3)

0.436

Self-reported at resurvey in the MWS

Birth weight (kg)

61

-0.1 (0.4)

45

-0.1 (0.6)

32

0.0 (0.4)

59

-0.1 (0.4)

37

-0.2 (0.4)

0.377

Mother's height (cm)

56

-0.1 (5.9)

102

-0.2 (4.2)

52

-0.6 (4.7)

24

-1.1 (5.6)

60

-3.1 (6.0)

0.007

Father's height (cm)

47

5.1 (7.0)

70

1.5 (5.2)

51

-2.2 (5.5)

28

-2.7 (7.1)

44

-1.8 (3.7)

<0.001

Waist circumference (cm)

53

-2.6 (4.5)

43

-4.2 (6.1)

49

-6.3 (6.3)

35

-7.3 (7.2)

26

-13.8 (9.1)

<0.001

Hip circumference (cm)

50

-0.7 (4.6)

53

-3.6 (5.3)

44

-2.6 (4.7)

31

-4.2 (4.9)

26

-6.6 (6.1)

<0.001

Waist-to-hip ratio

50

0.00 (0.04)

41

-0.03 (0.04)

37

-0.03 (0.05)

39

-0.05 (0.07)

30

-0.08 (0.06)

<0.001

Waist-to-height ratio

59

-0.02 (0.03)

40

-0.03 (0.04)

45

-0.03 (0.05)

33

-0.05 (0.04)

27

-0.08 (0.06)

<0.001


MWS: Million Women Study. NSHD: National Survey of Health and Development. N: numbers of women with non-missing values for both MWS and NSHD variables. SD: standard deviation of the mean error.

* Errors calculated as the difference (MWS value - NSHD value).

P-value for the F-test (ANOVA) for a difference, across quintiles of the NSHD data, in the mean error in the MWS self-reported values with respect to the NSHD values.

‡ Age at menarche categorised as <11, 11, 12, 13 or 14+ years, rather than by quintiles.

Cairns et al. BMC Medical Research Methodology 2011 11:7   doi:10.1186/1471-2288-11-7

Open Data