Comparison of food frequency questionnaires: the reduced Block and Willett questionnaires differ in ranking on nutrient intakes
Food frequency questionnaires, major tools in epidemiologic studies, are often criticized for biased and imprecise intake estimates. The aim of this study was to compare the performance of two widely used food frequency questionnaires, a reduced 60-item Block questionnaire and a 153-item Willett food frequency questionnaire, relative to three 24-hour recalls administered by telephone. The dietary