# 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.

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### Interpretation of kruskal wallis test results

Hello I have run a kruskal wallis test to compare the median between three groups as in this picture below: I know what median value and p value are but: IQR is the spread of data but what is used ...
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### Kruskal-Wallis test on data with heterogeneous variance and small sample sizes per group

I've been trying to figure out how to test (in R) if there are significant differences between the group means of my data because it seems to violate the assumptions of tests that do this (ANOVA, ...
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### Statistical analysis - Shapiro-Wilk test?

I apologize if this question will seem odd, but I am quite new to statistical analysis. I performed coinfection experiments with a total of 12 conditions, and I have 3 measurements per condition. I ...
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### Can the chi-square statistic in Kruskal-Wallis test be compared to determine the most appropriate to distinguish the groups?

I have a dataframe in R which format is similar as follows: v1 v2 v3 group 1 3.5 100 a 3 5 200 a 10 5.5 150 b 8 7.5 210 b 4 4.5 300 c 9 2.5 200 c ... My ...
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### Kruskal-Wallis versus Friedman - Paired data, but not repeated measures/blocks?

I'm trying to compare the difference in behaviour of an animal with no enrichment to the same animal with two (or more) types of enrichment. (Total active behaviours before/total active behaviours ...
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### Using multiple mean tests instead of linear model

First, I would like to apologize because I'm a beginner in statistics and I'm surely confused on some points. This is one of my first statistic work doing for university. I would like to explain a ...
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### How can I explain signifcant combined groups in Mann Whitney U but no individual effects in Kruskal Wallis?

I am struggling to get my head around the concepts of my tests and how to explain them. Unfortunately we didn't recieve much in depth teaching about it on my course. I have 4 variables, one is a ...
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### Which Significance test to apply to compare number of occurences of multiple events across multiple groups?

Our dataset is composed of time-series data (recordings) collected for 18 different groups (test conditions G0 to G17). The number of recordings per group can vary (30-600). For each of these ...
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### Dunn's post-hoc Test after Kruskal, 'which one is more effective?' after significant difference

Dunn's test yielded the result that there is a significant difference in revenue between group 1 and group 2 after Kruskal. In classic one way ANOVA case, if the result is same as above, you see ...
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### Appropriate statistical test to compare groups containing discrete data

I need to compare more than 2 groups, each containing discrete data (more specifically, integer numbers between 1 and 9). Shapiro-Wilk tests come back as significant for most groups, meaning the data ...
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### showing significance of gender differences in control vs treatment groups

I have 4 groups with independent samples : Female Control Female Treatment Male Control Male Treatment When I compare Control to Treatment within the same sex, I find that Female Control to Female ...
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### Is it appropriate to remove biologically meaningless pairwise comparisons after Dunn test for a post-hoc(FDR) analysis for multiple comparisons? [duplicate]

I have four individual groups(A, B, C, & D) Differences between the groups are being analyzed by the Kruskal-Wallis test followed by Dunn's test for multiple comparisons (dunnTest command in R). ...
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### After Dunn test with 4 groups, I got 6 p-values for 6 combinations. Can I just choose 4 of 6 p-values to get lower FDRs?

After Shapiro-test(p-value<0.05) and Kruskal-Wallis null rejection, Someone has done the Dunn test with 4 groups, He got 6 p-values for 6 combinations. Can he just choose 4 of 6 p-values to get ...
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### How to convert my output into a suitable table for ANOVA or Kruskwallis testing on SPSS?

Let's say I have asked an individual to classify images according to 3 fruits that he sees : apple, banana and kiwi. Then, I want to assess whether there are significant differences between the ...
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### Three-way manova or separate anovas?

I have three independent catagorial variables and two dependent continuous scale variables, so I want to compare means across these three independent catagorial variables. I think here the best choice ...
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### Does Kruskal-Wallis work as a two-way Anova in R? [duplicate]

I am trying to find a non-parametric two-way ANOVA test. My data can not be normalized I have tried everything. Many people say that Kruskal-Wallis is equivalent to a two-way ANOVA, except when I code ...
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### Urgent help! What statistical test to use (dental thesis) [duplicate]

The primary aim of this study is to compare tongue posture and function in children with an unilateral posterior crossbite UPCB who were treated with maxillary expansion in combination with orofacial ...
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### What statistical test to use (dental thesis)? [duplicate]

I am a fourth year dental student from Belgium and have to chose an appropriate statistical test for my thesis. I have to compare tongue posture and tongue position between 3 groups, but can't seem to ...
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### if I have a variable in my data that is not normally distributed, could I still use an ANOVA if my sample size is large enough?

I have a sample size that is more than 30 but one of my continuous variables is not normally distributed. The Shapiro-Willk test does say that my data is not normally distributed. I am going to ...
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### Effect size measure for post-hoc tests after nonparametric tests: Alternatives to calculating r from z score?

I've calculated Friedman's tests for my data and want to report an effect size with the individual post-hoc tests that followed on from the statistically significant Friedman's test. I use the formula ...
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### Which ANOVA / non-parametric alternative should I use?

Apologies if this is a really simple question but I cannot work it out. I am trying to find out if year and/or location influence the amount of insects caught. Insects are measured in grams per 10km2. ...
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### Evaluate significance for three different groups not normal distributed with different n

I have a group with three different treatments. One group gets shown 0 Tags, 4 and 7. N's are different in the range of 80-100 and data does not follow a normal distribution. I would also like to ...
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### Which Test to Run?

Please advise which statistical test (ordinal logistic regression or chi-square test) is most suitable in the following context: I want to test if the two independent variables (frequency of use of a ...
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### Can ordinal data be transformed to nominal data?

I have five variables all in the ordinal form. The measurement goes like this- 5- Strongly agree, 4- Agree, 3- Neither agree nor disagree, 2- Disagree, and 1- Strongly disagree. Now, out of the five ...
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### Kruskal Wallis test or ANOVA for G-mean?

I currently working on the data (4 groups), which requires the evaluation in Geometric means. I transform the data into logarithms (which is non-normal distributed), then I wonder whether to use ANOVA ...
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### Does Kruskal-Wallis test have a non-parametric analogue that isn't sensitive to groups having different variability?

I need a non-parametric test for my project (because I can't be sure that the distribution would always be normal), so I decided to use Kruskal-Wallis test. But the problem is that Kruskal-Wallis test ...
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### Why are the stated facts about using the Mann-Whitney U test for post-hoc testing after a Kruskal-Wallis test a problem?

I've read here on several threads that using Mann-Whitney U for post-hoc tests are an issue because: the ranks that the pair-wise rank sum tests use are not the ranks used by the Kruskal-Wallis test (...
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### Meta-analysis of data with no standard deviation

I am carrying out a Meta-analysis on the impacts of forest logging on Soil. One of the parameter which I want to investigate is the qbs-ar index, which is a index of soil biological quality. This ...
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### How do I interpret the p-value in a Dunn-test?

I conducted a Kruskal Wallis test for my sample sizes, and this is what I got: Kruskal-Wallis chi-squared = 12.138, df = 4, p-value = 0.01635 The p-value is below 0.05, so I know there is a ...
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### Kruskal Wallis on difference scores?

I'm wondering whether it's possible to do a Kruskal-Wallis test on difference scores, since I can't seem to find an example of this online. I think it would make sense conceptually, but I would like ...
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### How can we prove that kruskal wallis test and jonckheere test is equivalent to wilcoxon rank sum test?

How can we prove that kruskal-Wallis test and Jonckheere test is equivalent to Wilcoxon rank sum test when k = 2? And how can we prove that Friedman test and Page test is equivalent to sign test when ...
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### Significance testing the difference in dimensionality between conditions

I would like to test the hypothesis that under two experimental conditions there is a difference in data dimensionality. Measures of dimensionality are complicated statistics of the data; for example, ...
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### Compare multimodal distributions for different groups

I am analyzing data from 3 different gait speeds. For each group/speed, I am determining specific value called "angle". Each group has different sample size. So, I need to compare multimodal ...
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### Which is the most suitable non-parametric test (and post-hoc)for a heavily umbalanced groups (3, 15 and 11 observations)?

I am comparing soil properties among different geological substrates. I have only 3 observations in one category (karst soils), 15 observations in sedimentary terrains and 11 observations in ...
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### Is the Conover-Iman post-hoc test is better to use than Dunn's with small samples size after the KW test since it use the t-test on the ranks?

I know that we use the t-distribution to be able to know if two small-size samples with a normal distribution (n < 30) are different or not (Student's t-test). If we have a bigger sample with a ...
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### Kruskal-Walis interpretation with too many outliers and "0" values

I want to establish significant differences between certain groups. I have a dependent variable that is named "NRPS BGCs" which are the presence of certain genes founded in certain bacterial ...
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### kruskal-walis interpretation with too many outliers and "0" values

I want to establish significant differences between certain groups. I have a dependent variable that is named "NRPS BGCs" which are the presence of certain genes founded in certain bacterial ...
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### Statistical significance test of kurtosis differences

I would like to raise a problem that bothers me. However, I would like to point out right away that my question is purely theoretical, and the data presented here comes only from a computer experiment ...
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### Non-normal data, manova and kruskal_test

I am trying to perform a statistical test on a large data frame. For this, I was thinking to find differences between groups using MANOVA. I have 70 columns and 2 independent variables. In the example ...
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### Which pairwise comparison tests are best to use after the Kruskal-Wallis test (Dunn, Conover-Iman or Steel-Dwass-Critchlow-Fligner test)?

I have 3 sampling sites where I took 3 water samples in each site. I chose to do the Kruskal-Wallis test to find out if there is a significant difference in total nitrogen between the sites. I did not ...
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### What statistical test its appropriate for my experimental design?

i need some help with my research. I dont know if its possible to use a statistic test in my design. To exemplify, following the design: 1 - I fertilize and distribute 100 embryos in each well (W1, W2,...
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### is there any non parametric Welch's ANOVA?

I need to test for differences between non-normally distributed and heteroscedastic data. I know that I can use the Kruskal-Wallis test to assess significant differences between groups but one ...
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### Adjusted significance level in SPSS for Kruskal Wallis Post Hoc Test - Bonferroni adjustment

I am making a pairwise comparison using Dunn's post hoc test with Bonferroni correction. However, I am a bit confused on the interpretation of the adjusted significance on SPSS. I am making 10 ...
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### Analysis of count data: Poisson regression, chi square, or Kruskal-Wallis?

I have collected data on how many events occur (as counts) across three groups: control, sham, experimental. I have also collected continuous data such as body mass, wing length, along with age. My ...
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### How to report? Significant difference for Kruskal-Wallis test, but not for ad hoc pairwise comparison with Bonferroni

I performed Krusal-Wallis test in SPSS and got a borderline significant P (0.042). then, the post hoc pairwise comparison with Bonferroni-Dunn correction showed no pairwise significant difference. I ...
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### What does comparing mean rank mean?

Lets assume that I am having 2 samples: Sample A 20 20 20 20 25 and Sample B 1 2 3 4 5 If I want to compare these two samples ...
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### Kruskal-Wallis possible?

Let's assume the group variable is the dependent variable and can have the values [A,B,C,D]. It is nominal. The independent variable is ordinal and can have numbers between 0 and 5. I want to test for ...
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### Specifying non-linear mixed effects models or non-parametric ANCOVA in R (non-linear DV and covariate)

I tried running a standard mixed model in lme, and the residuals were highly non-normal, now I want to do a non-parametric version with a covariate and am having trouble. More details and data below. ...
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