Change search
ReferencesLink to record
Permanent link

Direct link
Intraclass correlation associated with therapists: estimates and applications in planning psychotherapy research
Department of Psychology, Brigham Young University, Provo, Utah, USA.
Division of Epidemiology, Ohio State University, Columbus, Ohio, USA.
School of Social Sciences, Humanities and Arts, University of California, Merced, Merced, California, USA.
Department of Psychology, University of Memphis, Memphis, Tennessee, USA.
Show others and affiliations
2011 (English)In: Cognitive Behaviour Therapy, ISSN 1650-6073, Vol. 40, no 1, 15-33 p.Article in journal (Refereed) Published
Abstract [en]

It is essential that outcome research permit clear conclusions to be drawn about the efficacy of interventions. The common practice of nesting therapists within conditions can pose important methodological challenges that affect interpretation, particularly if the study is not powered to account for the nested design. An obstacle to the optimal design of these studies is the lack of data about the intraclass correlation coefficient (ICC), which measures the statistical dependencies introduced by nesting. To begin the development of a public database of ICC estimates, the authors investigated ICCs for a variety outcomes reported in 20 psychotherapy outcome studies. The magnitude of the 495 ICC estimates varied widely across measures and studies. The authors provide recommendations regarding how to select and aggregate ICC estimates for power calculations and show how researchers can use ICC estimates to choose the number of patients and therapists that will optimize power. Attention to these recommendations will strengthen the validity of inferences drawn from psychotherapy studies that nest therapists within conditions.

Place, publisher, year, edition, pages
Routledge, Taylor and Francis Group , 2011. Vol. 40, no 1, 15-33 p.
Keyword [en]
statistical dependence; therapist effects; intraclass correlation; power; psychotherapy research
National Category
Research subject
URN: urn:nbn:se:umu:diva-40286DOI: 10.1080/16506073.2010.520731OAI: diva2:399179
Available from: 2011-02-21 Created: 2011-02-21 Last updated: 2011-06-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Carlbring, Per
By organisation
Department of Psychology
In the same journal
Cognitive Behaviour Therapy

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 72 hits
ReferencesLink to record
Permanent link

Direct link