Preprint

A common measurement scale for self-report instruments in mental health care: T scores with a normal distribution

This article is a preprint and has not been certified by peer review [What does this mean?].

Author(s) / Creator(s)

de Beurs, Edwin
Oudejans, Suzan
Terluin, Berend

Abstract / Description

The diversity of measures in clinical psychology hampers a straightforward interpretation of test results, complicates communication with the patient, and constitutes a challenge to the implementation of measurement-based care. In educational research and assessment, it is common practice to convert test scores to a common metric, such as T scores. We recommend to apply this also in clinical psychology and propose and test a procedure to arrive at T scores approximating a normal distribution, that can be applied to individual test scores. We established formulas to estimate normalized T scores from raw scale scores by regressing IRT-based theta scores on raw scores. With data from large population and clinical samples, we established crosswalk formulas. Their validity was investigated by comparing calculated T scores with IRT-based T scores. IRT and formulas yielded very similar T scores, supporting the validity of the latter approach. Theoretical and practical advantages and disadvantages of both approaches to convert scores to a common metric and alternative approaches are discussed. Provided that scale characteristics allow for their computation, T scores will help to better understand measurement results, which makes it easier for patients and practitioners to use test results in joint decision-making about the course of treatment.

Keyword(s)

IRT T scores percentile ranks common metric clinical norms

Persistent Identifier

Date of first publication

2022-03-30

Publisher

PsychArchives

Is version of

Citation

  • Author(s) / Creator(s)
    de Beurs, Edwin
  • Author(s) / Creator(s)
    Oudejans, Suzan
  • Author(s) / Creator(s)
    Terluin, Berend
  • PsychArchives acquisition timestamp
    2022-03-30T08:37:50Z
  • Made available on
    2022-03-30T08:37:50Z
  • Date of first publication
    2022-03-30
  • Abstract / Description
    The diversity of measures in clinical psychology hampers a straightforward interpretation of test results, complicates communication with the patient, and constitutes a challenge to the implementation of measurement-based care. In educational research and assessment, it is common practice to convert test scores to a common metric, such as T scores. We recommend to apply this also in clinical psychology and propose and test a procedure to arrive at T scores approximating a normal distribution, that can be applied to individual test scores. We established formulas to estimate normalized T scores from raw scale scores by regressing IRT-based theta scores on raw scores. With data from large population and clinical samples, we established crosswalk formulas. Their validity was investigated by comparing calculated T scores with IRT-based T scores. IRT and formulas yielded very similar T scores, supporting the validity of the latter approach. Theoretical and practical advantages and disadvantages of both approaches to convert scores to a common metric and alternative approaches are discussed. Provided that scale characteristics allow for their computation, T scores will help to better understand measurement results, which makes it easier for patients and practitioners to use test results in joint decision-making about the course of treatment.
    en
  • Publication status
    other
  • Review status
    notReviewed
  • Persistent Identifier
    https://hdl.handle.net/20.500.12034/5063
  • Persistent Identifier
    https://doi.org/10.23668/psycharchives.5665
  • Language of content
    eng
  • Publisher
    PsychArchives
  • Is version of
    https://doi.org/10.1027/1015-5759/a000740
  • Is related to
    https://www.psycharchives.org/handle/20.500.12034/5060
  • Is related to
    https://www.psycharchives.org/handle/20.500.12034/5061
  • Is related to
    https://www.psycharchives.org/handle/20.500.12034/5062
  • Keyword(s)
    IRT
    en
  • Keyword(s)
    T scores
    en
  • Keyword(s)
    percentile ranks
    en
  • Keyword(s)
    common metric
    en
  • Keyword(s)
    clinical norms
    en
  • Dewey Decimal Classification number(s)
    150
  • Title
    A common measurement scale for self-report instruments in mental health care: T scores with a normal distribution
    en
  • DRO type
    preprint