help:wilcoxon

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 — help:wilcoxon [2010/12/20 23:36] (current) Line 1: Line 1: + [[http://​www.sofastatistics.com/​userguide.php | Contents]] + [[:​help:​stats_tests | Statistical Tests Available]] + + ====== Wilcoxon Signed Ranks ====== + + The Wilcoxon Signed Ranks Test (see [[http://​en.wikipedia.org/​wiki/​Wilcoxon_signed-rank_test | Wilcoxon signed-rank test]]) is useful for looking at differences in two variables. ​ The data must be paired e.g. looking at pre and post-diet weight. ​ The variables being averaged must also be measured at an interval level of measurement. + + If your data is numerical and is adequately normally distributed,​ you may be better using the [[:​help:​paired_ttest | paired t-test]]. + + If you are looking at independent/​unpaired data e.g. height between two countries, the non-parametric equivalent is the [[:​help:​mann_whitney | Mann-Whitney U Test]]. + + The p value tells you how likely the difference observed would occur if sampling from a population in which there is no actual difference. A small p value tells you that it would be rare to observe such a difference if there is no actual difference between the variables. From this we might reject the null hypothesis in favour of the alternative hypothesis - namely, that there is a difference. + + Be aware that there is a certain sensitivity about terminology around this area.  According to a widespread convention, we shouldn'​t conclude that there is a relationship,​ only that we reject the null hypothesis (see [[http://​www.stats.gla.ac.uk/​steps/​glossary/​hypothesis_testing.html#​h0 | Hypothesis testing]]). We might go so far as to reject the null hypothesis in favour of the alternative hypothesis. ​ See [[http://​en.wikipedia.org/​wiki/​Statistical_hypothesis_testing | Statistical hypothesis testing]]. + + [[http://​www.sofastatistics.com/​userguide.php | Contents]] + + [[:​help:​stats_tests | Statistical Tests Available]] + + [[:home | Wiki]]
help/wilcoxon.txt · Last modified: 2010/12/20 23:36 (external edit)

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