Adherence
A semiquantitative food frequency questionnaire (FFQ) provides valid and reproducible estimates of individual nutrient intakes over a one-year period, making it suitable for large-scale epidemiological studies of chronic disease.
For large population studies, a simple food frequency questionnaire is a valid tool to estimate long-term nutrient intake. It may not capture exact daily amounts, but it reliably ranks people by their typical intake, which is sufficient for identifying dietary risk factors for chronic diseases like heart disease and cancer.
These data indicate that a simple self-administered dietary questionnaire can provide useful information about individual nutrient intakes over a one-year period.
Why this rating
The study uses a robust design with 173 participants, four weeks of diet records as a reference, and statistical validation of reproducibility and validity, though it is a single cohort study.
Source
REPRODUCIBILITY AND VALIDITY OF A SEMIQUANTITATIVE FOOD FREQUENCY QUESTIONNAIRE
Walter C. Willett et al. · American Journal of Epidemiology · 1985
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