title: Incorrect use of the student t test in randomized trials of bilateral hip and knee arthroplasty patients.
abstract: The statistical analysis of a study's results is critical to its interpretation. Often confused, 2 types of t tests exist for dependent or independent samples. We reviewed randomized controlled trials that included patients undergoing bilateral total hip or knee arthroplasty (dependent samples) that used the t test for analysis. Our inclusion criteria resulted in 40 studies for review, 10 of which combined both unilateral and bilateral patients. Of the 30 studies that compared a pure sample of only bilateral patients, 18 (60%) incorrectly used the independent t test. Of the 10 studies with mixed samples, 8 (80%) used the independent t test. The extent to which the incorrect use of this statistical test led to misleading conclusions is uncertain; however, our findings highlight the misuse of statistical tests in the arthroplasty literature.
authors.affiliation: Division of Orthopaedic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Gandhi
authors.forename: Holly N
authors.initials: HN
authors.lastname: Smith
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Mahomed
authors.forename: Randy
authors.initials: R
authors.lastname: Rizek
authors.forename: Mohit
authors.initials: M
authors.lastname: Bhandari
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D019645:Arthroplasty, Replacement, Knee / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D006621:Hip Joint / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D015233:Models, Statistical; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*