On the reliability and standard errors of measurement of contrast measures from the D-KEFS

John Robertson Crawford, David McGregor Sutherland, Paul H. Garthwaite

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46 Citations (Scopus)


A formula for the reliability of difference scores was used to estimate the reliability of Delis-Kaplan Executive Function System (D-KEFS; Delis et al., 2001) contrast measures from the reliabilities and correlations of their components. In turn these reliabilities were used to calculate standard errors of measurement. The majority of contrast measures had low reliabilities: of the 5 1 reliability coefficients calculated in the present study, none exceeded 0.7 and hence all failed to meet any of the criteria for acceptable reliability proposed by various experts in psychological measurement. The mean reliability of the contrast scores was 0.27, the median reliability was 0.30. The standard errors of measurement were large and, in many cases, equaled or were only marginally smaller than the contrast scores' standard deviations. The results Suggest that, at present, D-KEFS contrast measures should not be used in neuropsychological decision making. (JINS, 2008, 14, 1069-1073.)

Original languageEnglish
Pages (from-to)1069-1073
Number of pages5
JournalJournal of the International Neuropsychological Society
Issue number6
Early online date27 Oct 2008
Publication statusPublished - Nov 2008


  • executive functioning
  • neuropsychological assessment
  • difference scores
  • psychometrics
  • measurement error
  • quantitative methods
  • executive function system


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