Skip to main content

Table 4 Over- and under-reporting in quantitative MWS variables by quintiles of corresponding NSHD data

From: Lifetime body size and reproductive factors: comparisons of data recorded prospectively with self reports in middle age

  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
  1. 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.
  2. * Errors calculated as the difference (MWS value - NSHD value).
  3. 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.
  4. ‡ Age at menarche categorised as <11, 11, 12, 13 or 14+ years, rather than by quintiles.