Non-parametric tests. Note: When valid use parametric Commonly used Wilcoxon Chi square etc. Performance comparable to parametric Useful for non-normal data If normalization not possible Note: CI derivation-difficult/impossible. Wilcoxon signed rank test. - PowerPoint PPT Presentation
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Chi square etc.
Wilcoxon signed rank test
To test difference between paired data
one sum would be much smaller and
the other much larger than expected
3rd & 4th ranks are tied hence averaged
T= smaller of T+ (50.5) and T- (4.5)
Here T=4.5 significant at 2% level indicating the drug (hypnotic) is more effective than placebo
* 17, 18 & 19are tied hence the ranks are averaged