Instrument to evaluate the combination of foods to make iron more bioavailable in the diet

Abstract

The scope of this research was to develop an instrument to evaluate the knowledge which adult women have of food combinations in order to make iron bioavailable in the diet of children. An exploratory factor analysis study (Likert scale) was conducted applying a questionnaire on a sample comprising 151 women and then applying Principal Factor Analysis and Likelihood Ratio Analysis. The Kaiser-Meyer-Olkin (KMO) test, the Doornik-Hansen test, the Kaiser Guttman criterion and the correlation between factors and theoretical assumptions were applied. Reliability was assessed by Cronbach's alpha and composite reliability. Total KMO (0.5942) showed the adequacy of the sample. The Doornik-Hansen test showed multivariate normality of the scores observed. Factorial loads, error variance of items and correlation between factors pointed to the two-dimensional nature of the questionnaire, which decreased from 30 to 15 items. Total Cronbach's alpha was 0.8018 (95% CI = 0.7429 to 0.8606) and composite reliability (Factor 1 = 0.3125 and Factor 2 = 0.3263). Convergent and discriminant factorial validity revealed acceptable results. A decision was taken to reduce the instrument (from 30 to 15 items) with sufficient reliability and validity that enable it to qualify for further confirmatory factor analysis procedures.