Intraclass correlation coefficients (ICCs) are often used when estimating reliability, but they are not always correctly interpreted in orthopedic research. Lee et al. (1) reviewed 92 published orthopedic articles that presented ICCs for reliability estimation with regard to how they were documented.

Of all these articles, published between January 1992 and May 2010, 58 (63%) did not clarify the ICC model used. This was clearly described in only 5 (5%) of the articles. This means, of course, that the results cannot have been correctly interpreted by the readers.

The authors conclude that appropriate ICC models, types, and measures should be selected based on the context of the investigation, and that studies that use ICCs for reliability test should clearly describe the ICC model, type, and measures. The authors also provide a guideline for this.


1. Lee KM, Lee J, Chung CY, Ahn S, Sung KH, Kim TW, Lee HJ, Park MS. Pitfalls and Important Issues in Testing Reliability Using Intraclass Correlation Coeffi cients in Orthopaedic Research. Clin Orthop Surg 2012;4:149-155