Psychometric properties of the short and ultra-short versions of socioeconomic status assessment tool for health studies in Iran (SES-Iran)

Abstract

Purpose: The aim of this study was to curtail the full version of instrument by 50% (short version) and 25% (ultra-short version) of its original size (22 items) and evaluate the reliability and validity of both versions. Methods: The experts’ comments were used to make short and ultra-short versions. The two versions were evaluated by use of indicators related to reliability (internal consistency and test-retest) and diagnostic validity, diagnosis of marginal areas from central areas using ROC curve analysis, among 1600 households. Also, intraclass correlation coefficient (ICC), Pearson correlation coefficient and Bland-Altman plot were used in order to assess agreement between full and shortened versions. Results: The short and ultra-short versions were included 10 items and 6 items, respectively. Cronbach’s Alpha was 0.83 and 0.65 for short version and ultra-short version respectively. The Pearson correlation coefficient and the coefficient of agreement were desirable and acceptable for both versions (p<001). Because of high agreement between shortened versions and full version, the two shortened versions measured the socioeconomic status as good as the full version. Meanwhile, the results were confirmed by means of Bland-Altman plot. Conclusion: Both short version and ultra-short version had suitable validity and reliability. As a result, both questionnaires can be used by researchers.