title: Dietary assessment instruments are susceptible to intervention-associated response set bias.
abstract: OBJECTIVE
  Evaluations of trials of the effectiveness of dietary intervention programs may be compromised by response set biases, such as those attributable to social desirability. Participants who receive a behavioral intervention may bias their reports of diet to appear in compliance with intervention goals. This study examined whether responses to standard dietary assessment instruments could be affected by a brief dietary intervention.
  
  
  METHODS
  We assigned 192 undergraduate students randomly to (a) see a 17-minute videotape on the consequences of eating a high-fat diet or a placebo videotape on workplace management and (b) receive preintervention and post-intervention assessments or only postintervention assessment. Dietary assessments included 4 independent measures of fat intake.
  
  
  RESULTS
  Among women, bias (intervention minus control) was -9.7 g fat (from a short food frequency questionnaire) and -0.6 high-fat foods (from a questionnaire about use of 23 foods in the previous day) (P < .05 for both). No results were significant among men or for 2 instruments that measured more qualitative aspects of fat-related dietary habits.
  
  
  CONCLUSIONS
  Even a modest dietary intervention can affect responses to dietary assessment instruments. Nutritionists should recognize that assessment of adherence to dietary change recommendations, when based on dietary self-report, can be overestimated as a result of response set biases.
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Kristal
authors.forename: C H
authors.initials: CH
authors.lastname: Andrilla
authors.forename: T D
authors.initials: TD
authors.lastname: Koepsell
authors.forename: P H
authors.initials: PH
authors.lastname: Diehr
authors.forename: A
authors.initials: A
authors.lastname: Cheadle
mesh_terms: D000328:Adult; D015982:Bias; D004041:Dietary Fats / Q000008:administration & dosage*; D005247:Feeding Behavior / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D012928:Social Desirability; D011795:Surveys and Questionnaires; D014743:Videotape Recording
chemical_list: D004041:Dietary Fats