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Table 4 Validation tests comparing dietary choline intake between the semiquantitative food frequency questionnaire and 24-hour recall interviews

From: Development and validation of a quantitative choline food frequency questionnaire for use with drinking and non-drinking pregnant women in Cape Town, South Africa

  Group-level agreement Individual-level agreement Summary
Agreement Agreement Agreement Bias Strength of association Agreement including chance Agreement excluding chance
Wilcoxon signed rank test p Percentage difference Bland-Altman LOA index Bland-Altman Spearman correlation p Spearman correlation2 Tertile classification Kappa statistic Group-level tests at “Good” or “Acceptable” (of 4 tests) Individual-level tests at “Good” or “Acceptable” (of 5 tests)
Same tertile Opposite tertile Weighted for tertiles Above vs. below AI
Heavy drinkers:
 Visit 1 (n = 121) .258 M 30.8% 5.0% .11 .39 48.8% 14.9% .26 .21 3 3
 Interpretation1 Good Poor Good Good Acceptable Poor Poor Acceptable Acceptable   
 Visits 1-2 (mean) (n = 116) .976 M 16.6% 8.0% .552 .39 46.6% 10.3% .31 .20 3 3
 Interpretation1 Good Acceptable Poor Good Acceptable Poor Poor Acceptable Acceptable   
 Visits 1-3 (mean) (n = 78) 1.00 M -9.5% 5.1% .148 .43 47.4% 7.7% .40 .18 4 2
 Interpretation1 Good Good Good Good Acceptable Poor Poor Acceptable Poor   
Abstainers/light-drinkers:
 Visit 1 (n = 83) .440 M 7.2% 4.8% .04 (.23) .51 50.6% 9.9% .39 .35 4 5
 Interpretation1 Good Good Good Poor Good Good Good Acceptable Good   
 Visits 1-2 (mean) (n = 68) .366 M 0.0% 4.2% .269 .52 50.0% 8.8% .42 .35 4 5
 Interpretation1 Good Good Good Good Good Good Good Acceptable Acceptable   
 Visits 1-3 (mean) (n = 42) 1.00 M 5.2% 2.4% .171 .56 45.0% 10.0% .33 .63 4 4
 Interpretation1 Good Good Good Good Good Poor Good Acceptable Good   
  1. 1Interpretation criteria [37]:
  2. Wilcoxon signed rank test: Good: p > 0.05; Poor: p ≤ 0.05
  3. Percentage difference: Good: 0.0 – < 11%; Acceptable: 11 - 20.0%; Poor: > 20%
  4. Bland-Altman LOA index (% outside of limit of agreement): Good: ≤ 5%; Poor: > 5%
  5. Bland-Altman Spearman correlation coefficient: Good: p > 0.05; Poor: p ≤ 0.05
  6. Spearman correlation coefficient: Good: ≥ 0.50; Acceptable: 0.20 – 0.49; Poor < 0.20
  7. Tertile classification (% in same tertile): Good: ≥ 50%; Poor: < 50%
  8. Tertile classification (% in opposite tertile): Good: ≤ 10%, Poor: > 10%
  9. Weighted Kappa statistic: Good: ≥ 0.60; Acceptable: 0.20 – 0.59; Poor: < 0.20
  10. 2p < .001 for all Spearman values
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