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Table 6 Validity of FFQ: Pearson’s correlation coefficient analysis of agreement and cross-classification analysis for energy and nutrient intakes as reported in FFQ1 and 24Hs among the school-aged children in Cambodia (n = 107)

From: Development and validation of a food frequency questionnaire (FFQ) for assessing dietary macronutrients and calcium intake in Cambodian school-aged children

Energy and nutrients Pearson's correlation coefficient % classified into same ±1 quartiled % Mis-classifiedd
Crude Energy-adjusteda Transformedb De-attenuated transformedc
Energy 0.53** 0.50** 0.71 81 7
Protein 0.50** 0.33** 0.44** 0.62 79 6
Fat 0.33** 0.18 0.29** 0.38 68 6
Carbohydrates 0.53** 0.31** 0.51** 0.70 81 5
Calcium 0.50** 0.46** 0.45** 0.59 81 6
  1. *Significant (p < 0.05), **Highly significant (p < 0.01)
  2. aAdjustment for energy was done by the residual method
  3. bTransformed: values were log-transformed
  4. cDe-attenuated: values calculated as the ratio of within-person to between-person variation estimated in the two 24-h recall surveys. The formula for calculating de-attenuated values was (1+ (S2w/S2b) n) 0.5, where S2w is within-person variation and S2b is between-person variation. n = 2
  5. dCross-classification analyses were completed to validate agreement between FFQ1 and 24Hs in terms of the proportions of participants classified into the same ±1 quantile or misclassified. FFQ food frequency questionnaire, FFQ1 the first FFQ, 24Hs the mean of the two 24-h recall surveys