Design, Conduct, and Interpretation of Nonrandomized Orthopaedic Studies--A Practical Approach   |    
Evaluating Agreement: Conducting a Reliability Study
Paul J. Karanicolas, MD, PhD1; Mohit Bhandari, MD, MSc, FRCSC1; Hans Kreder, MD, FRCSC2; Antonio Moroni, MD3; Martin Richardson, MD4; Stephen D. Walter, PhD1; Geoff R. Norman, PhD1; Gordon H. Guyatt, MD, MSc1
1 Department of Clinical Epidemiology and Biostatistics, McMaster University, 293 Wellington Street North, Suite 110, Hamilton, ON L8L 2X2, Canada. E-mail address for M. Bhandari: bhandam@mcmaster.ca
2 Department of Surgery, University of Toronto, Sunnybrook Campus, MG365, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada
3 Rizzoli Orthopaedic Institute, University of Bologna, Via G.C. Pupilli 1, Bologna 40136, Italy
4 Department of Orthopaedic Surgery, Royal Melbourne Hospital, University of Melbourne, Grattan Street, Parkville 3050, Melbourne, Victoria, Australia
View Disclosures and Other Information
Collaboration for Outcome Assessment in Surgical Trials (COAST) Musculoskeletal Group Steering Committee: Antonio Barquet, Uruguay; Ole Brink, Denmark; Hans Kreder, Canada; Takashi Matsushita, Japan; Antonio Moroni, Italy; Martin Richardson, Australia; Parag Sancheti, India; Paul Tornetta III, USA
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from the Canadian Institutes of Health Research. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2009 May 01;91(Supplement 3):99-106. doi: 10.2106/JBJS.H.01624
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Instruments that are useful in clinical or research practice will, when the object of measurement is stable, yield similar results when applied at different times, in different situations, or by different users. Studies that measure the relation of differences between patients or subjects and measurement error (reliability studies) are becoming increasingly common in the orthopaedic literature. In this paper, we identify common aspects of reliability studies and suggest features that improve the reader's confidence in the results. One concept serves as the foundation for all further consideration: in order for a reliability study to be relevant, the patients, raters, and test administration in the study must be similar to the clinical or research context in which the instrument will be used. We introduce the statistical measures that readers will most commonly encounter in reliability studies, and we suggest an approach to sample-size estimation. Readers interested in critically appraising reliability studies or in developing their own reliability studies may find this review helpful.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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