Using validity theory and psychometrics to evaluate and support expanded uses of existing scales

Carrie R. Houts, Elizabeth Nicole Bush, Michael C. Edwards, R. J. Wirth

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Background: Scale development is a complex activity requiring significant investments of time and money to produce evidence of a scale’s ability to produce reliable scores and valid inferences. With increasing use of clinical outcome assessments (COAs) in medical product development, evidentiary expectations of regulatory bodies to support inferences are a key consideration. The goal of this paper is to demonstrate how existing methods in measurement science can be used to identify and fill evidence gaps when considering re-purposing an existing scale for a new use case (e.g., new patient population, altering the recall period), rather than creating a new COA tool. Methods: We briefly review select validity theory and psychometric concepts, linking them to the nomenclature in the COA/regulated space. Four examples (two in-text and two in online supplemental materials) of modifications are presented to demonstrate these ideas in practice for quality of life (QOL)-related measures. Results: Each example highlights the initial process of evaluating the desired validity claims, identifying gaps in evidence to support these claims, and determining how such gaps could be filled, often without having to develop a new measure. Conclusions: If an existing scale, with minimal modification or additional evidence, can be shown to be fit for a new purpose, considerable effort can be saved and research waste avoided. In many cases, a new instrument is simply unnecessary. Far better to recycle an “old” scale for a new use–with sufficient evidence that it is fit for that purpose–than to “buy” a new one.

Original languageEnglish (US)
Pages (from-to)2969-2975
Number of pages7
JournalQuality of Life Research
Volume31
Issue number10
DOIs
StateAccepted/In press - 2022
Externally publishedYes

Keywords

  • Clinical outcome assessments
  • Fit-for-purpose
  • Psychometrics
  • Validity theory

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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