Journal of Clinical Epidemiology
Volume 54, Issue 1 , Pages 86-92 , January 2001

Should we always choose a nonparametric test when comparing two apparently nonnormal distributions?

  • Eva Skovlund

      Affiliations

    • Norwegian Cancer Society and Section of Medical Statistics, University of Oslo, Oslo, Norway
    • Corresponding Author InformationCorresponding author. Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway. Tel.: +47 22 93 47 56; fax: +47 22 50 91 99.(E. Skovlund)
  • ,
  • Grete U. Fenstad

      Affiliations

    • Department of Mathematics, University of Oslo, Oslo, Norway

Received 27 October 1998 ,Revised 19 April 2000 ,Accepted 20 April 2000.

References 

  1. Welch BL. The significance of the difference between two means when the population variances are unequal. Biometrika. 1937;29:350–362
  2. Chand U. Distributions related to comparison of two means and two regression coefficients. Ann Math Stat. 1950;21:507–522
  3. Wetherill GB. The Wilcoxon test and non-null hypotheses. J Roy Statist Soc (Series B). 1960;22:402–418
  4. Van der Vaart HR. On the robustness of Wilcoxon's two-sample test. In:  Jonge HD editors. Quantitative methods in pharmacology. New York: Interscience; 1961;
  5. Pratt JW. Robustness of some procedures for the two-sample location problem. JASA. 1964;59:665–680
  6. Lehmann EL. Nonparametrics (statistical methods based on ranks). San Francisco: Holden-Day; 1975;
  7. Fenstad GU. A comparison between the U and V tests in the Behrens-Fisher problem. Biometrika. 1983;70:300–302
  8. Zimmerman DW, Zumbo BD. Parametric alternatives to the student t test under violation of normality and homogeneity of variance. Percept Mot Skills. 1992;74:835–844
  9. Bridge PD, Sawilowsky SS. Increasing physicians' awareness of the impact of statistics on research outcomes (comparative power of the t-test and Wilcoxon rank-sum test in small samples applied research). J Clin Epidemiol. 1999;552:229–235
  10. Aurlien E, Holte H, Pharo A, et al.  Combination chemotherapy with mitoguazon, ifosfamide, MTX, etoposide (MIME) and G-CSF can efficiently mobilize PBPC in patients with Hodgkin's and non-Hodgkin's lymphoma. Bone Marrow Transplant. 1998;21:873–878
  11. Birtwistle GM, Dahl OJ, Myhrhaug B, Nygaard K. Simula begin. Bromley: Chartwell-Bratt Ltd; 1983;
  12. Fenstad GU, Skovlund E. The Behrens-Fisher problem: a comparison of test properties when observations are not necessarily normal. Statistical Research Report 10. University of Oslo: Department of Mathematics, 1992.

PII: S0895-4356(00)00264-X

Journal of Clinical Epidemiology
Volume 54, Issue 1 , Pages 86-92 , January 2001