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help:wilcoxon [2010/12/20 23:36] (current)
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 +[[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.
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 +If your data is numerical and is adequately normally distributed,​ you may be better using the [[:​help:​paired_ttest | paired t-test]].
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 +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]].
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 +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.
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 +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]].
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 +[[http://​www.sofastatistics.com/​userguide.php | Contents]]
 +
 +[[:​help:​stats_tests | Statistical Tests Available]]
 +
 +[[:home | Wiki]]
help/wilcoxon.txt ยท Last modified: 2010/12/20 23:36 (external edit)