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Table 4 Summary of Validity Assessments Between the FFQ and 24-h Recalls for Fermented and Non-Fermented Foods

From: Prevalence of fermented foods in the Dutch adult diet and validation of a food frequency questionnaire for estimating their intake in the NQplus cohort

Method % Difference Correlation Coefficient Quintile Cross-Classification Bland-Altmana
Aspect of Validity Measured Agreement (group level) Strength and direction of association (individual level) Agreement (individual level) Presence, direction, and extent of bias (group level)
Interpretation Criteria Acceptable: 0.0 to 10.0%
Poor: > 10%
Good: ≥0.50
Acceptable: 0.20 to 0.39 (lower range); 0.40 to 0.49 (higher range)
Poor: < 0.20
Good: ≥50% in same/adjacent quintile; ≤5% in extreme quintile
Poor: < 50% in same/adjacent quintile; > 5% in extreme quintile
Good: p > 0.05
Poor: p ≤ 0.05
Fermented beverages Acceptable Good Good Good
 Coffee Acceptable Good Good Good (bias)
 Beer Poor Good Good Good (bias)
 Wine Poor Good Good Poor (bias)
Fermented cereals/grains Acceptable Good Good Poor
 Brown bread Acceptable Acceptable (low) Poor Good (bias)
 White bread Poor Acceptable (low) Good Poor (bias)
 Wholegrain bread Acceptable Good Good Good
 Rye bread Acceptable Acceptable (high) Good Good (bias)
 Other bread Poor Poor Poor Good (bias)
 Pastries Poor Acceptable (low) Poor Good (bias)
Chocolate Poor Acceptable (low) Good Poor (bias)
Fermented dairy Acceptable Good Good Good
 Cheese Acceptable Acceptable (high) Good Good (bias)
 Yoghurts Poor Good Good Poor
 Quark Poor Poor Poor Poor (bias)
 Buttermilk Poor Poor Poor Poor (bias)
Non-fermented dairy Poor Good Good Poor
 Butter Acceptable Acceptable (high) Good Good (bias)
 Cream Poor Acceptable (low) Poor Poor (bias)
 Ice cream Poor Acceptable (low) Poor Poor (bias)
 Milk Poor Good Good Poor
Non-fermented soya Poor Acceptable (high) Good Good (bias)
  1. FFQ Food frequency questionnaire. Acceptable and good validity assessment outcomes are bolded.
  2. aThe presence of proportional bias for each food group is indicated in brackets