# Questions tagged [kruskal-wallis]

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.

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### Wrong Intepretation of Kruskal Wallis Test in R

I have some data (called egecNonmated) in R and I am trying to show that the distributions of a variable (MatchScore) are identical across three different Categories (Cat). I am using a box plot to ...
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### Variance assumption and normal assumption not met, Kruskal or Welch-Anova?

I have 7 different groups of playing time data that is not normal. Lets say its really not normal..like a lot. The variance is also not equal and fails the bartlett test by a landslide. Sample ...
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### How to implement ordinal logistic regression for a factorial design

I have read a few answers (e.g. this, this and this) recommending to use Ordinal Logistic Regression (OLR) as a generalized method when Kruskal-Wallis is not suitable. For instance, a 2x2 factorial ...
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### Any other non-parametric alternative to Kruskal-Wallis?

It looks like Kruskal-Wallis is the standard nonparametric test for more than two groups. The problem is that it does not tell which groups are different, except that whether there exists significant ...
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### What are the consequences of using ANOVA instead of Kruskal-Wallis on non-normally distributed data?

I am doing a high-school statistics assignment and am having trouble finding answer to this question. Anova and Kruskal-Wallis test are very confusing and I am lost trying to find and explanation to ...
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### Rank sums in the Kruskal-Wallis output

I use Stata to perform a Kruskal-Wallis test on four groups of data (not normally distributed), and the results are shown below: ...
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### Relationship between nominal and ranked variables

I am practicing statistics on the gss dataset. I want to study the relationship between people owning guns in the USA and political inclination. Owning guns or not is a nominal variable while ...
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### Statistical significance test: One way Anova and Kruskal-Wallis test

I was comparing data between two groups and for each group there was six samples. My data are as follows: group 1: 103.56, 103.32, 103.32, 104.27, 103.56, 103.8 group 2: 97.16, 97.16, 96.69, 98.58, ...
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### GLM post hoc with non-parametric tests?

I have a question regarding the appropriate use of comparisons for independent samples (3 factor levels). Overall sample size is N=546, subsamples: 218 or 228 or 100), convenience sampling, stratified....
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### Which post-hoc comparison to use and why

Hopefully this is now a much clearer picture of the question I want to answer: For each of 60 different plans I ran 35 simulation replications of my Agent Based Model (ABM) simulation. Then for each ...
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### Factorial design for interactions with ordinal DV

I want to make a 4 question, multiple choice survey in which each question asks about an analogous range of actions for slightly different scenarios. Each participant would only be administered the ...
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### Why am I getting inconsistent results from Wilcoxon signed rank test and Kruskal-Wallis test?

I am doing a study on 3 drugs, comparing response pre-post treatment. My objective is to know if these drugs are effective and which one is better. I used non parametric tests since the results weren'...
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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 ...
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### Comparing transaction counts between samples

I have a treatment group and two control groups for customers and the count of their transactions: ...
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### Kruskal-Wallis and Dunn's

I am trying to interpret the results of some experiments I have run, involving showing participants videos of animated synthesised speech. I ran a mean opinion score test. I made 36 movies in total. ...
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### Multiple Sample Equality-of-Distributions Test For Panel Data

Suppose I have repeated time observations for 800 meter sprint for a group of athletes over the course of a season. I would like to test the hypothesis that all the times are drawn from the same ...
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### Repeated measure two-way ANOVA (non-parametric)

Non-parametric ANOVA ā a hot topic that is unanswered. There are many questions on this topic online. However, they all seem to end in a debate and no definite answer or clear explanation (that I ...
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### Independent Variable groups w/ n=1 possible for Kruskal Wallis?

I am working with clinical data with 7 groups that constitute my independent variable and a not normally distributed dependent variable. I know I have to use KW test to check for significant ...
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### Kruskal-Wallis test is not significant but some of the Mann-Whitney comparisons are significant

I have a non-normalized dependent variable and an independent variable broken down into 4 groups. As such, I used the KruskalāWallis analysis to look for significant differences in the ranks of the ...
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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 ...
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### Kruskal-Wallis test for factorial design [duplicate]

Is it possible to use the Kruskal-Wallis test for two factors and their interaction (i.e., two way ANOVA: Y~a*b)? And which post-hoc test is possible to use after ...
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### Kruskal-Wallis?

I have three sets of data (1 set before treatment, second during treatment and the third after), each of which consists of hundreds of trials on a specific task that involves choosing 1 from 7 ...
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### Similarity of time series

I try to find out the smallest window size for calculating statistical values on a stream. To illustrate my problem: I record the average car counts per brand on a street using different sliding ...
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### Interpret the pairwise comparison plot from SPSS [closed]

For my user study, I am trying to find out to what extent people prefer to move by foot. They had the option to rank their preference for 'walking', 'jogging' and 'running' for a several amount of ...
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### Comparing reaction tests

I have an experiment where every person needs to take reaction tests when he/she is sober, then when lightly and then heavily intoxicated. I need to perform a test that tells if the intoxication had ...
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### Alternative to Friedman test for single treatments (no repetitions)

I'm looking for a non-parametric (!) alternative to the Friedman test. I have > 2 subjects and measured one quantity per subject. I want to know whether there is a significant difference between any ...
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### Kruskal-Wallis Test and Mann-Whitney U Test

I have a three samples of data where each has a non-normal distribution: I want to determine whether the samples differ. Therefore I apply the KW test and it gives me a significant value, i.e. the ...
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### Mean ranks and standard errors of Kruskal-Wallis test

While it's easy to compute the p-value of Krsukal-Wallis non-parametric test using the kruskal.test() function, I don't know how to compute the mean ranks and ...
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### Are pairwise Wilcoxon tests a valid non-parametric alternative to Tukey's HSD test?

I am trying to identify significant differences between groups from normal and non-normal distributions. When the distribution is normal the workflow is pretty straightforward: ANOVA and after that a ...
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### Are very low ANOVA and Kruskal Wallis p-values reason to doubt the results?

I have four relatively small sets of data under five different conditions. For each set of data I want to see whether the differences between the conditions are statistically significant. The first ...
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### How to report Kruskal-Wallis test?

As part of the analysis of the data collected from a survey, I was carrying out Kruskal-Wallis Tests between some Likert scale questions and demographics such as firm size and job position. I am using ...
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### Influence of two factors on non-normal outcome. Which test?

I measured two variables (outcomes) $Y_a$ and $Y_b$ for several subjects. $Y_a$ and $Y_b$ are continuous variables defined on $[0,100]$ and have a bimodal distribution. I tried using a transformation ...
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### Non-normal distribution even with Kruskal-Wallis test

Thanks to anyone who can help! I`ve done a survey with Likert-scale questions with about 1,500 participants. Initial analysis in SPSS showed no outliers (using box-plot) but scores were not normally ...
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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 ...
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### Differences between Dwass-Steel-Critchlow-Fligner and Mann-Whitney U-test for a post-hoc pairwise analysis

If you have one control and four groups of patients with a non-normal small sample size, there are differences in these tests for a post-hoc analysis after Kruskal-Wallis?
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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?
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### Paired t-test, Kruskal-Wallis rank sum test and chisquare test. Which test should I choose?

I observed moth oviposition in orchard for 4 moths (400 clusters per week). The moth oviposit on leaf and apple. I want to compare the means between oviposit on leaf and apple. I suppose to use paired ...
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### Correlation with non-normal distribution [duplicate]

I want to find the correlation between a continous variable with a non normal distribution, positively skewed, and a categorical variable with 4 categories. The only test I can find that fits these ...
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### Kruskal Wallis test with high type 1 error

using this code ...
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### Five different groups

We are running a study which investigates platelet aggregation changes during three trimesters of pregnancy and postnatal period. Then we compare each of these phases to control non-pregnant women. ...
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### Test selection for group comparison

We are running a study which investigates platelet aggregation changes during three trimesters of pregnancy and postnatal period. Then, we compare each of these phases to control non-pregnant women. ...
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### ANOVA / Kruskal-Wallis: one of four groups has different distribution

I'm using Kruskal-Wallis to as a non-parametric ANOVA of a non-normal distribution. My understanding is that it assumes each group of the independent variable has the same shape. As it turns out, ...
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### Analysis of Similarities (ANOSIM) versus Kruskal-Wallis

What is the difference between the two sets of statistic tests? Which is recommended for finding out if the difference between groups is more significant than within groups, for non-parametric ...
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### Exact probability and asymptotic approximation

From Wikipedia A large amount of computing resources is required to compute exact probabilities for the Kruskal-Wallis test. Existing software only provides exact probabilities for sample sizes ...
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### Difference between disease conditions by non-parametric ANOVA

I've the following simplified data as shown. ...
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### Ranks test problem

This is a questions I got for homework in test planning and variance analysis. I apologize in advance for the way my professor phrases things :D I would love to hear hints or tips on how to approach ...
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### Confusion related to kruskal wallis test

I have some confusion related to Kruskal wallis test. I have an example lets say X=[2 2 35 10 9 8 11 12]; Y=[1 1 1 2 2 2 2 2]; Y is the group variable Now when ...
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### Kruskal-Wallis test of groups with unequal sample sizes matlab

I can't seem to work out why I can't perform a 5 grouped Kruskal-Wallis test on unequal sample sizes in matlab. Any thoughts how to do this? Also as a post-hoc analyis using Wilcoxon Rank sum is this ...