© 2018 Journal of Renal Nutrition and Metabolism | Published by Wolters Kluwer - Medknow 15
Abstract
A questionnaire by definition is a set of leading questions applied to assess opinions related to an issue, situation or event, or measure statistics if applied to a large group of people. In most population-based dietary studies, the questionnaire is the only instrument that connects the researcher with the respondent. Through the questionnaire, the researcher is expected to ‘gauge’ what is on the mind of the respondent. If this tool is not valid, then the findings will not be useful at all.
The task of constructing, testing and validating a questionnaire is not as easy as it may look. There are many different forms of questionnaire applied to gauge the health of the chronic disease population. To note are the SF-36 to assess the quality of life, IPAQ to assess level of physical activity and the food frequency questionnaire developed to local context. Whatever the form, if a questionnaire is newly designed or adopted from published literature, the intention of the researcher is to understand there are limitations and advantages in its application.
In questionnaire design, the researcher defines a concept and tries to operationalize it by asking several questions, called items. Then the question arises: are the items measuring what they are intended to? To answer this, the questionnaire must undergo a rigorous process of validation.
First the items must be content validated. Usually a panel of experts will be asked to test the content of the questionnaire.
Based on the panel’s opinion, some items may be deleted, modified or added. In case the questionnaire need to be
translated, a forward and backward translation must be performed by bilingual personnel.
In the pilot test stage, the Cronbach’s Alpha could be used to indicate internal consistency. A test-retest could be performed to test for repeatability. Factor analysis may show the underlying structures. A confirmatory factor analysis must be used to confirm whether the items are adequately measuring the concept. Further, the questionnaire must be able to withstand the factorial invariance test procedures.
This short presentation will introduce the idea that questionnaire whether innovated or adapted must by design be rigorously scrutinized before been launched in a research project.
Questionnaire Validation in Dietary Studies
Karuthan Chinna, PhD
Associate Professor, Faculty of Health & Medical Sciences, Taylor’s University, Malaysia
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DOI:
10.4103/2395-1540.232545
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How to cite this article: Chinna K. Questionnaire validation in dietary studies. J Renal Nutr Metab 2018;3:15.
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