Rapid detection of differential item functioning in assessments of health-related quality of life: The Functional Assessment of Cancer Therapy

Paul K. Crane*, Laura E. Gibbons, Kaavya Narasimhalu, Jin Shei Lai, David Cella

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Reason for study: Differential item functioning (DIF) occurs when a test item functions differently in different groups when controlling for the level of the underlying construct measured by the test. DIF assessment is a first step in the evaluation of test bias. We sought to demonstrate a rapid hybrid approach to DIF detection by determining the presence and scale-level impact of DIF related to eight covariates in four domains measured by the Functional Assessment of Cancer Therapy (FACT). Major findings: The number of items found with DIF in each domain depended on the criterion chosen to define the presence of DIF. With a few exceptions, scale-level differential functioning was similar regardless of the criteria chosen. For physical well-being, there was relevant scale-level differential functioning related only to race. For social and family well-being, there was relevant scale-level differential functioning related to each of the covariates. For emotional well-being, there was relevant scale-level differential functioning related to ethnicity, language, and race. For functional well-being, there was relevant scale-level differential functioning related to ethnicity, race, education, and self- vs. interviewer-administration. Principal conclusions: Our rapid hybrid approach to DIF detection may be broadly applicable in other studies of health-related quality of life.

Original languageEnglish (US)
Pages (from-to)101-114
Number of pages14
JournalQuality of Life Research
Volume16
Issue number1
DOIs
StatePublished - Feb 2007

Keywords

  • Differential item functioning
  • Item response theory
  • Ordinal logistic regression
  • Test bias

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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