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Validation Information: FFQ
Comparison of a Food Frequency Questionnaire with a Diet Record
The associations between levels of nutrients derived from a 24-hour diet record and a food frequency questionnaire were assessed in a sample of 433 men and women. The food frequency questionnaire was administered three years after the completion of the diet record. Spearman correlations were all statistically significant; they varied from 0.36 for energy to 0.15 for vitamin A. Comparison of distributions into fifths showed few people grossly misclassified. A model was developed to assess the correlations which would be expected under various conditions of within and between subject variance for each nutrient, errors in measurements and drift in intake over time. The best possible correlation that could be obtained using the within and between subject variations in intake previously published, and with no measurement error or drift over time, was 0.60 for energy and 0.34 for vitamin A. Using a realistic measure of measurement error (standard deviation on log scale of 0.12 for diet record method, 0.06 for drift over time and 0.18 for food frequency method) the correlations obtained in the modelling were very similar to that observed. This study shows that it may be appropriate to use a food frequency questionnaire instead of a diet record to estimate intakes in population based epidemiological studies.
Total number of nutrients validated: 9
Not all of the nutrients validated in the validation studies are included in the table below, as statistical data was only selected to be displayed for a number of nutrients, this included:
- Saturated Fat
- Mono-unsaturated Fat
- Poly-unsaturated Fat
- Non‐starch polysaccharides(NSP)
- Folic Acid
- Vitamin B12
- Vitamin C
- Fruit & Vegetables
- Urinary Nitrogen
To find information on the other validated nutrients please read the validation study.
- Macronutrients: 4
- Micronutrients: 4
|Comparator||Lifestage||Sex||Nutrient Measured||Mean Difference||Standard Deviation||Correlation Coefficient||Cohen's Kappa Coefficient||Percentage Agreement||Percentage Agreement Categories||Lower Limits of Agreement||Upper Limits of Agreement|
|24hr Recall||Adults||Both||Energy (kcal)||0.36 (S)||27||5|
|Energy (kJ)||0.36 (S)||27||5|
|Protein (g)||0.22 (S)||24||5|
|Fat (g)||0.36 (S)||26||5|
|Carbohydrates (g)||0.30 (S)||24||5|
|Calcium (mg)||0.21 (S)||23||5|
|Vitamin C (mg)||0.24 (S)||24||5|
Some results have been calculated using statistical techniques based on the published data.
For further information on statistical terms click on Statistical tests used in validation studies
All correlations coefficients in the table are unadjusted unless stated otherwise. For adjusted correlation coefficients and other statistical methods used in the study e.g. paired t-tests, please read the validation articles.
- # Adjusted
- † Energy adjusted.
- ‡ For loge-transformed, energy-adjusted nutrient intakes.
- ^ Adjacent included.
- ᵟ Participants provided identical responses.
- (w) = Weighted.
Margetts BM, Cade JE, Osmond C. Comparison of a food frequency questionnaire with a diet record. International Journal of Epidemiology. 1989 Dec 1;18(4):868-73.