Computerized adaptive testing of population psychological distress: simulation-based evaluation of GHQ-30

Jan Stochl (Lead / Corresponding author), Jan Boehnke, Kate E. Pickett, Tim J. Croudace (Lead / Corresponding author)

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    8 Citations (Scopus)
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    Purpose: Goldberg’s General Health Questionnaire (GHQ) items are frequently used to assess psychological distress but no study to date has investigated the GHQ-30’s potential for adaptive administration. In computerized adaptive testing (CAT) items are matched optimally to the targeted distress level of respondents instead of relying on fixed-length versions of instruments. We therefore calibrate GHQ-30 items and report a simulation study exploring the potential of this instrument for adaptive administration in a longitudinal setting.

    Methods: GHQ-30 responses of 3445 participants with 2 completed assessments (baseline, 7-year follow-up) in the UK Health and Lifestyle Survey were calibrated using item response theory. Our simulation study evaluated the efficiency of CAT administration of the items, cross-sectionally and longitudinally, with different estimators, item selection methods, and measurement precision criteria.

    Results: To yield accurate distress measurements (marginal reliability at least 0.90) nearly all GHQ-30 items need to be administered to most survey respondents in general population samples. When lower accuracy is permissible (marginal reliability of 0.80), adaptive administration saves approximately 2/3 of the items. For longitudinal applications, change scores based on the complete set of GHQ-30 items correlate highly with change scores from adaptive administrations.
    Conclusions: The rationale for CAT-GHQ-30 is only supported when the required marginal reliability is lower than 0.9, which is most likely to be the case in cross-sectional and longitudinal studies assessing mean changes in populations. Precise measurement of psychological distress at the individual level can be achieved, but requires the deployment of all 30 items.
    Original languageEnglish
    Pages (from-to)895-906
    Number of pages12
    JournalSocial Psychiatry and Psychiatric Epidemiology
    Issue number6
    Early online date21 Dec 2015
    Publication statusPublished - Jun 2016


    • Computerized adaptive testing
    • Item response theory
    • Bifactor model
    • Measurement invariance


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