Development and validation of Transtheoretical model-based questionnaire on micronutrients for adolescents:...

The Transtheoretical model (TTM) is one of the most commonly used theories in assessing behavioral change and designing more effective interventions. The study aimed to develop and validate a questionnaire based on the TTM to assess the behavioral change of adolescent girls related to dietary micronutrient intake.

A TTM-based questionnaire (Items 36) was validated through 150 adolescent girls aged 13-18 years. The questionnaire is made on four constructs: stages of change, processes of change, self-efficacy, and decision balance. The content validity and face validity were assessed by expert panels and participants, respectively. The confirmatory factor analyses (CFA) were used to test construct validity. The Cronbach's alpha coefficient and Intraclass Correlation Coefficient (ICC) were used to analyze the internal consistency and stability of the questionnaires.

Results showed that all content validity Index values of items in questionnaires were within the range (0.8-1). Based on face validity results, most of the items were clear, easy, and understood by participants. The CFA results included a comparative factor index of 0.99 for all constructs; a goodness of fit index ranging from 0.88 to 0.951, and a root mean square error of approximation ranging from 0.039-0.069, suggesting good model fit indices. The reliability analysis with Cronbach's alpha of 0.737-0.953 and ICCs of 0.737-0.845 was acceptable.

These psychometric analysis results provided evidence for the appropriateness, reliability, and validity of the developed questionnaire. Hence, this questionnaire may help to develop customized nutrition intervention programs based on behavioral changes in the context of micronutrient intake.