title: Relative validity of a short qualitative food frequency questionnaire for use in food consumption surveys.
abstract: BACKGROUND
  The aim of the present study was to assess the relative validity of a self-administered qualitative food frequency questionnaire (FFQ) applied in the Belgian food consumption survey.
  
  
  METHODS
  Comparison of food consumption data from an FFQ with 7-day estimated diet records (EDR) was made in a sample of 100 participants (aged 15-90 years). The FFQ comprised a total of 50 foods. Both FFQ and EDR foods were categorized into 15 conventional food groups.
  
  
  RESULTS
  De-attenuated Spearman rank correlation coefficients between the FFQ and the EDR ranged from -0.16 for potatoes and grains to 0.83 for alcoholic beverages, with a median of 0.40 for all 15 food groups. The proportion of participants classified in the same tertile of intake by the FFQ and EDR ranged from 32% for potatoes and grains to 76% for alcoholic beverages. Extreme classification into opposite tertiles was <10% for milk and soy products, alcoholic beverages, fried restgroup foods and fats.
  
  
  CONCLUSIONS
  Notwithstanding the short nature and the absence of portion size questions, the FFQ appears to be reasonably valid in both genders and across different age categories for most food groups. However, for the food groups bread and cereals, potatoes and grains, and sauces, estimates should be interpreted with caution because of poor ranking agreement.
authors: 1 Department of Nutrition and Dietetics, Faculty of Health Care Vesalius, University College Ghent, Ghent, Belgium.
authors: Willem
authors: W
authors: De Keyzer
authors: Arnold
authors: A
authors: Dekkers
authors: Veerle
authors: V
authors: Van Vlaslaer
authors: Charlene
authors: C
authors: Ottevaere
authors: Herman
authors: H
authors: Van Oyen
authors: Stefaan
authors: S
authors: De Henauw
authors: Inge
authors: I
authors: Huybrechts
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001530:Belgium; D003430:Cross-Sectional Studies; D015930:Diet Records; D005247:Feeding Behavior; D005260:Female; D005502:Food / Q000145:classification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015203:Reproducibility of Results; D057566:Self Report; D012737:Sex Factors; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult