In our study, “Interleukins 17 and 10 in a Sample of Egyptian Relapsing Remitting Multiple Sclerosis Patients”, we adopted a well-organized statistical plan. The normality testing, using Kolmogorov-Smirnov and Shapiro-Wilk test, was performed [
] using “SPSS Explore” procedure (Analyze → Descriptive Statistics → Explore → Plots → Normality plots with tests) [
- Oztuna D.
- Elhan A.H.
- Tuccar E.
Investigation of four different normality tests in terms of type 1 error rate and power under different distributions.
Turkish J. Med. Sci. 2006; 36: 171-176
]. The P value of K-S test of normality for all values was less than 0.05 and the same applied for Shapiro-Wilk P value with positively skewed distribution on the histogram. In such non-normally distributed sample, Mann-Whitney test (also called Mann–Whitney–Wilcoxon (MWW), or Wilcoxon–Mann–Whitney test) was used [
- Elliott A.C.
- Woodward W.A.
Statistical Analysis Quick Reference Guidebook with SPSS Examples.
first ed. Sage Publications, London2007
] to compare results of unrelated (independent) groups, as the nonparametric counterpart of the student's unpaired t-test, and Wilcoxon signed rank test was applied to compare the results of related (dependent) samples (MS patients during relapse and in remission), as the nonparametric counterpart of the student's paired t-test. The P-value shown in table comparing multiple sclerosis patients before and after relapse is the value from Wilcoxon test.
- Fay M.P.
- Proschan M.A.
Wilcoxon-Mann-Whitney or t-test? On assumptions for hypothesis tests and multiple interpretations of decision rules.
Stat Surv. 2010; 4: 1-39
To read this article in full you will need to make a payment
Purchase one-time access:Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
One-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:Subscribe to Journal of the Neurological Sciences
Already a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
- Investigation of four different normality tests in terms of type 1 error rate and power under different distributions.Turkish J. Med. Sci. 2006; 36: 171-176
- Statistical Analysis Quick Reference Guidebook with SPSS Examples.first ed. Sage Publications, London2007
- Wilcoxon-Mann-Whitney or t-test? On assumptions for hypothesis tests and multiple interpretations of decision rules.Stat Surv. 2010; 4: 1-39
- Individual comparisons by Ranking Methods.Biom. Bull. 1945; 1: 80-83
- On a test of whether one of two random variables is stochastically larger than the other.Ann. Math. Stat. 1947; 18: 50-60
Published online: April 26, 2017
Accepted: April 25, 2017
Received: April 20, 2017
© 2017 Published by Elsevier B.V.