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Revista de Saúde Pública

Print version ISSN 0034-8910On-line version ISSN 1518-8787


SANTOS, Kionna Oliveira Bernardes; CARVALHO, Fernando Martins  and  ARAUJO, Tânia Maria de. Internal consistency of the self-reporting questionnaire-20 in occupational groups. Rev. Saúde Pública [online]. 2016, vol.50, 6.  Epub Mar 22, 2016. ISSN 0034-8910.


To assess the internal consistency of the measurements of the Self-Reporting Questionnaire (SRQ-20) in different occupational groups.


A validation study was conducted with data from four surveys with groups of workers, using similar methods. A total of 9,959 workers were studied. In all surveys, the common mental disorders were assessed via SRQ-20. The internal consistency considered the items belonging to dimensions extracted by tetrachoric factor analysis for each study. Item homogeneity assessment compared estimates of Cronbach’s alpha (KD-20), the alpha applied to a tetrachoric correlation matrix and stratified Cronbach’s alpha.


The SRQ-20 dimensions showed adequate values, considering the reference parameters. The internal consistency of the instrument items, assessed by stratified Cronbach’s alpha, was high (> 0.80) in the four studies.


The SRQ-20 showed good internal consistency in the professional categories evaluated. However, there is still a need for studies using alternative methods and additional information able to refine the accuracy of latent variable measurement instruments, as in the case of common mental disorders.

Keywords : Mental Health; Questionnaires, utilization; Reproducibility of Results; Validation Studies; Mental Disorders, diagnosis; Workers.

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