Dietary Assessment Methods An Overview Zuzana Derflerová Brázdová Masaryk University of Brno Context of the Diet in Human Life Culture Diet Policy Community Language Social norms l Physiological needs Behavior Psychological needs Environment What do we know about human diet without doubts and EXACTLY? lPeople eat. C:\Program Files\Microsoft Office\Clipart\standard\stddir2\ED00087_.wmf Comparison of Qualitative and Quantitative Methods l Qualitative Quantitative lParadigm Construction Objectivism lPurpose Often: Exploratory Confirmatory lPerspective Emic (insider) Etic (outsider) lSample Size Generally: Small Large lSampling methods Purposive Random lUnits of Analysis Words Numbers lStrengths Depth, context Testing relations l generalizability The Qualitative – Quantitative Continuum l lQualitative Quantitative l Continuum of Structure l lUnstructured interviews Freelisting Structured surveys lParticipant observations Pile Sorting Structured l observations l lSemistructured interviews, Open-ended lFocus group discussions survey questions Triangulation lTriangulation means that you measure some variables more than one way, maximizing the chance for uncovering the truth lMethods used depend on: time, research capacity, resources, beliefs… lExample – Assess. of the prevalence of exclusive breastfeeding at the age 3 mos (Malawi): lAll methods Diet history 7 days rec. 24h rec. l14.1% 20.9% 31.7% 38.8% Approaches to Combining Methods I. lModel 1: lQualitative method informs development of quantitative instruments l l Qualitative Quantitative Approaches to Combining Methods II. Quantitative lModel 2: lQualitative data help explain quantitative findings Qualitative Approaches to Combining Methods III lModel 3: lCombined approach l l l Qualitative Quantitative Qualitative Focus Groups l Semi-structured vs In-Depth Interview l Qualitative Data Analysis Approach lContinuous, iterative process involving the following basic components: lIn the field l Reading Coding Reducing Displaying Interpreting At your desk Analytical Techniques lContent Analysis lMatrix Analysis lNarrative Case Analysis lEthnographic Decision-Models lDomain Analysis lMultidimensional Scales lTaxonomic Analysis Observational Methods l Quantitative Methods I. Prospective lRecord (3 days, 7 days) l weight, estimated lStrengths: lMore exact than recall, does not rely on memory lWeaknesses: lRely very much on people’s compliance lRequires: literacy, responsibility, stable living conditions… Quantitative Methods II. Prospective lHousehold Inventory usually 1,3,6,12 moss lStrengths: exact, combine nutrit. and econom. data lWeaknesses: does not reflect individual’s consumption l lMethod of Double Portions lStrength: exact, allows detailed chemical analysis lWeakness: requires high level of compliance, stable living conditions, is expensive, causes inconvenience l Quantitative Methods III. Retrospective lRecall: usually 24 h, sometimes 3 days l --- Weight l --- Estimated (Photo book, 3D models) l lStrengths: easy, quick, cheap, useful in large samples lWeaknesses: less representative, rely on memory, requires kitchen/serving literacy, not possible in children<7 yrs l Quantitative Methods IV. Retrospective lFood frequency questionnaire l Semi-quantitative l Quantitative l lStrengths: lCovers long period, not influenced by short term changes lWeaknesses: reflects more people’s desire than reality, less exact, not possible in children<7yrs Quantitative Analysis l