Statistical Analysis Stack Exchange
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Questions tagged [kruskal-wallis-test]

The Kruskal–Wallis procedure is a nonparametric equivalent of one way analysis of variance, used for comparing the location of three or more groups; it extends the two sample Mann–Whitney–Wilcoxon procedure.

The Kruskal–Wallis procedure is a nonparametric equivalent of one way analysis of variance, used for comparing the location of three or more groups; it extends the Mann–Whitney–Wilcoxon, which is used for two samples. It is effectively ANOVA applied to the ranks of the data.

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Difference Between ANOVA and Kruskal-Wallis test

I am learning R and have been experimenting with analysis of variance. I have been running both kruskal.test(depVar ~ indepVar, data=df) and anova(lm(depVar ~ indepVar, data=dF)) Is there a practical difference between these two tests? My…
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Is there an equivalent to Kruskal Wallis one-way test for a two-way model?

If the model does not satisfy ANOVA assumptions (normality in particular), if one-way, Kruskal-Wallis non-parametric test is recommended. But, what if you have multiple factors?
user4267
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Post-hoc tests after Kruskal-Wallis: Dunn's test or Bonferroni corrected Mann-Whitney tests?

I have some non-Gaussian distributed variable and I need to check if there are significant differences between the values of this variable in 5 different groups. I have performed Kruskal-Wallis one-way analysis of variance (which came up…
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Power analysis for Kruskal-Wallis or Mann-Whitney U test using R?

Is it possible to perform a power analysis for the Kruskal-Wallis and Mann-Whitney U test? If yes, are there any R packages/functions that perform it?
Giorgio Spedicato
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How to read the results of Dunn's test?

How do I read the results from Dunn's test? Specifically, what do the values in the table below tell me? I have non-parametric data in 4 groups, and I first did a Kruskal-Wallis test to confirm that the groups' distributions were dissimilar from…
bubbalouie
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Multiple comparisons in a non-parametric test

I am working with a data set that is non-parametric and has 12 treatments. I performed the Kruskal-Wallis test and got a significant $p$-value, and now I would like to conduct a multiple comparisons procedure to see which of the treatments differ…
jesse
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Which result to choose when Kruskal-Wallis and Mann-Whitney seem to return contradicting results?

I have these groups where the values are responses to a 10-point Likert item: g1 <- c(10,9,10,9,10,8,9) g2 <- c(4,9,4,9,8,8,8) g3 <- c(9,7,9,4,8,9,10) Therefore I used Kruskal-Wallis to determine any differences between responses in the groups, and…
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Should I report non-significant results?

I've run a Kruskal Wallis test, and for some of the questions the p value is not significant. Would I report this in the same way as if it was significant, stating the df, test statistic and p-value? So it would be something like this a Kruskal…
Dragonfly
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Friedman vs Kruskal-Wallis test

I have read the Wikipedia pages for Friedman's and Kruskal-Wallis' test, but I am not sure which one to use. Are there differences in the assumptions?
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Benjamini-Hochberg dependency assumptions justified?

I have a data set where I test for significant differences between three populations with respect to some 50 different variables. I do this using Kruskal-Wallis tests, on one hand, and by likelihood ratio tests of nested GLM model fits (with and…
user14867
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Slight inconsistency between the Kruskal-Wallis built-in R function and manual calculation

I'm confused by the following, and I haven't been able to dig up the answer elsewhere. I'm trying to learn R while doing some statistics, and, as an exercise, I try to double-check the results of the built-in R functions by also doing these 'by…
MSR
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Testing the difference of (some) quantile-Q between groups?

For some Y variable, that is divided into 3 groups (X), I wish to compare the groups and for the hypothesis that the 90% quantile is the same between all three groups. What tests can I use? One option I can think of is using quantile regression,…
Tal Galili
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Can Mann-Whitney test be used for post-hoc comparisons after Kruskal-Wallis?

I have a simulation where an animal is placed in a hostile environment and timed to see how long it can survive using some approach to survival. There are three approaches it can use to survive. I ran 300 simulations of the animal using each…
Phlox Midas
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Strange result of post-hoc test

I have data for a test on three groups. The measured variable is ratio scaled. The R code is g1a<-c(7, 3, 40) g2a<-c(1,1,2) g3a<-c(0,0,0) Since the sample is small and normality cannot be guaranteed, I run a Kruskal Wallis test to check for…
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Multiple comparisons with many groups

I would like to determine if using multiple comparisons test would be appropriate for my data. I used the Kruskal-Wallis test to determine if there were differences in mean inhibition among $17$ different groups. The analysis revealed that there…
Matt
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