Mokken scaling and principal components analyses of the CORE-OM in a large clinical sample

Bedford, A., Watson, R., Lyne, J., Tibbles, J., Davies, F. and Deary, I.J. (2010) Mokken scaling and principal components analyses of the CORE-OM in a large clinical sample. Clinical Psychology and Psychotherapy, 17 1: 51-62. doi:10.1002/cpp.649

Author Bedford, A.
Watson, R.
Lyne, J.
Tibbles, J.
Davies, F.
Deary, I.J.
Title Mokken scaling and principal components analyses of the CORE-OM in a large clinical sample
Journal name Clinical Psychology and Psychotherapy   Check publisher's open access policy
ISSN 1063-3995
Publication date 2010-01-01
Year available 2009
Sub-type Article (original research)
DOI 10.1002/cpp.649
Volume 17
Issue 1
Start page 51
End page 62
Total pages 12
Editor Mick Power
Paul Emmelkamp
Place of publication West Sussex, England, U.K.
Publisher John Wiley and Sons
Language eng
Subject C1
920210 Nursing
111099 Nursing not elsewhere classified
Abstract In a sample of 543 adult National Health Service (NHS) patients referred to a Psychological Therapies Service, the responses to the Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) self-report questionnaire were examined using conventional principal components analysis (PCA) and a unique application of Mokken Scaling Procedure (MSP). Following the theoretical views of G. A. Foulds, it was suggested that some items more properly belong to the universe of attitudes and traits rather than that of symptoms and states. Accordingly, the analyses were carried out both with and without the CORE-OM Risk domain items. Both PCAs produced a very large first component of Psychological distress, while the small second component differs. With all items included, the second component was of Risk. With the risk items excluded, the second component was now Functioning. The MSP results, respectively, were of a five-item scale of Functioning (impaired by depression) and on the second analysis, a five-item Functioning scale (impaired by anxiety). There was discussion on the criteria for item selection, the time scale specified in questionnaire instructions and the optimum number of items required for a symptom scale. It was concluded that the CORE-OM item pool did not conform to its purported face validity domains and subdomains, but predominantly constitutes a large Psychological distress scale with considerable item redundancy.
Keyword CORE_OM
Mokken Scaling Procedure (MSP)
Principal Component Analysis (PCA)
Q-Index Code C1
Q-Index Status Provisional Code

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Nursing, Midwifery and Social Work Publications
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Citation counts: TR Web of Science Citation Count  Cited 17 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 08 Mar 2010, 23:25:38 EST by Vicki Percival on behalf of School of Nursing, Midwifery and Social Work