tailieunhanh - Báo cáo khoa học: "úp cho các bạn có thêm kiến thức về ngành y học đề tài: Statistics review 10: Further nonparametric methods"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Statistics review 10: Further nonparametric methods. | Critical Care June 2004 Vol 8 No 3 Bewick et al. Review Statistics review 10 Further nonparametric methods Viv Bewick1 Liz Cheek2 and Jonathan Ball3 Senior Lecturer School of Computing Mathematical and Information Sciences University of Brighton Brighton UK 2Senior Lecturer School of Computing Mathematical and Information Sciences University of Brighton Brighton UK 3Senior Registrar in ICU Liverpool Hospital Sydney Australia Corresponding author Viv Bewick Published online 16 April 2004 Critical Care 2004 8 196-199 DOI cc2857 This article is online at http content 8 3 196 2004 BioMed Central Ltd Abstract This review introduces nonparametric methods for testing differences between more than two groups or treatments. Three of the more common tests are described in detail together with multiple comparison procedures for identifying specific differences between pairs of groups. Keywords Friedman test Jonckheere-Terpstra test Kruskal-Wallis test least significant difference Introduction The previous review in this series 1 described analysis of variance the method used to test for differences between more than two groups or treatments. However in order to use analysis of variance the observations are assumed to have been selected from Normally distributed populations with equal variance. The tests described in this review require only limited assumptions about the data. The Kruskal-Wallis test is the nonparametric alternative to one-way analysis of variance which is used to test for differences between more than two populations when the samples are independent. The Jonckheere-Terpstra test is a variation that can be used when the treatments are ordered. When the samples are related the Friedman test can be used. Kruskal-Wallis test The Kruskal-Wallis test is an extension of the Mann-Whitney test 2 for more than two independent samples. It is the nonparametric alternative to one-way analysis of variance. Instead of comparing .