Table 4 |
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|
Over- and under-reporting in quantitative MWS variables by quintiles of corresponding NSHD data |
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|
1st quintile |
2nd quintile |
3rd quintile |
4th quintile |
5th quintile |
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|
|
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|
Variable (units) |
N |
mean error (SD)* |
N |
mean error (SD)* |
N |
mean error (SD)* |
N |
mean error (SD)* |
N |
mean error (SD)* |
P† |
|
|
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|
Self-reported at recruitment in the MWS |
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|
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 |
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|
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 |
|
|
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|
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. |
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|
Cairns et al. BMC Medical Research Methodology 2011 11:7 doi:10.1186/1471-2288-11-7 |
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