title: Internal consistency of the self-reporting questionnaire-20 in occupational groups.
abstract: OBJECTIVE
  To assess the internal consistency of the measurements of the Self-Reporting Questionnaire (SRQ-20) in different occupational groups.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Departamento de Biofunção, Universidade Federal da Bahia, Salvador, BA, Brasil.
authors.forename: Kionna Oliveira Bernardes
authors.initials: KO
authors.lastname: Santos
authors.affiliation: Departamento de Medicina Preventiva, Universidade Federal da Bahia, Salvador, BA, Brasil.
authors.forename: Fernando Martins
authors.initials: FM
authors.lastname: Carvalho
authors.affiliation: Departamento de Saúde, Universidade Estadual de Feira de Santana, Feira de Santana, BA, Brasil.
authors.forename: Tânia Maria
authors.initials: TM
authors.lastname: de Araújo
mesh_terms: D000328:Adult; D001938:Brazil; D004522:Educational Status; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis*; D008875:Middle Aged; D016272:Occupational Health; D011594:Psychometrics; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires