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- Wirfält, Elisabet, et al.
(författare)
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Comparison of food frequency questionnaires: the reduced Block and Willett questionnaires differ in ranking on nutrient intakes
- 1998
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Ingår i: American Journal of Epidemiology. - 0002-9262. ; 148:12, s. 1148-1156
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Tidskriftsartikel (refereegranskat)abstract
- 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 data were collected in 1991 from a group of healthy women age 25-49 years (n=101) during the baseline period of a weight-loss intervention study in Minneapolis, Minnesota. Total energy and macro- and micronutrient intakes were compared across methods by using four analytic approaches: comparison of means and correlation coefficients, regression analysis, and estimation of percent agreement between each questionnaire and recalls. The Block instrument showed an overall underestimation bias, but was more successful in categorizing individuals on percent energy from fat and carbohydrate intakes than was the Willett instrument. The Willett instrument showed no overall underestimation bias and was more successful in classifying individuals on vitamin A and calcium intakes. Diverging performance characteristics of diet assessment methods have an implication for the design of studies, interpretation of results, and comparison of findings across studies.
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| 2. |
- Wirfält, Elisabet, et al.
(författare)
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Using cluster analysis to examine dietary patterns: nutrient intakes, gender, and weight status differ across food pattern clusters
- 1997
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Ingår i: Journal of the American Dietetic Association. - 0002-8223. ; 97:3, s. 272-279
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study explored the usefulness of cluster analysis in identifying food choice patterns of three groups of adults in relation to their energy intake. DESIGN: Food frequency data were converted to percentage of total energy from 38 food groups and entered into a cluster analysis procedure. Subjects in the emerging food group patterns were compared in terms of weight status, demographics, and the nutrition composition of their usual diet. SETTING: Data were collected as part of three studies in two US metropolitan areas using identical protocols. Participants were university employees (103 women and 99 men) who volunteered for a reliability study of health behavior questionnaires and moderately obese volunteers (223 women and 101 men) to two weight-loss studies who were recruited by newspaper advertisements. STATISTICAL ANALYSIS PERFORMED: Subjects were clustered according to food energy sources using the FASTCLUS procedure in the Statistical Analysis System. One-way analysis of variance and chi 2 analysis were then performed to compared the weight status, nutrient intakes, and demographics of the food patterns. RESULTS: Six food pattern clusters were identified. Subjects in the two clusters associated with high consumption of pastry and meat had significantly higher fat intakes (P = .0001). Subjects in two other clusters, those associated with high intake of skim milk and a broad distribution of energy sources had significantly higher micronutrient levels (P = .0001). Body mass index and the distribution of gender were also significantly different across clusters. CONCLUSIONS: The success of cluster analysis in identifying dietary exposure categories with unique demographic and nutritional correlates suggests that the approach may be useful in epidemiologic studies that examine conditions such as obesity, and in the design of nutrition interventions.
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