# 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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### ANOVA/Kruskal Wallis on groups with several attributes

I was requested to do an ANOVA test (or a Kruskal Wallis one) on unpaired groups where each subject in a groups has several attributes/features. For example, I have groups 1,2,3... etc. Where each ...
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### Is Dunn-Sidak approach in MATLAB multcompare identical to so-called Dunn's test?

I've asked the same question elsewhere. These two articles recommend Dunn's test as non-parametric post hoc multiple comparison test following Kruskal-Wallis test. How the Dunn method for ...
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### Ways to state relationships like “A explains x% the variation in B” but when variation is not present like for non-parametric tests

Example: Income explains 70% of the variance in expenditure. Variation in driving speed can be explained by drivers' age. How does one make such statements if the test used is a non-parametric one? I ...
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### Checking ANOVA for unbalanced data

I would like to figure out if there are significant differences between the following groups. I use R: ...
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### What test to use when the dependent variable is an integer but independent variable is categorical? (Data non-normal, unequal variances)

My independent variable is species (categorical). My dependent variable is the total mass of what each species ate (in grams, numerical). I want to test the difference in mass values between ...
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### How to plot the results of a Kruskal-Wallis or a Welch's ANOVA?

Let's assume that I have two datasets for which I have measured three continuous variables. In both datasets, these variables have been measured on three groups of observations and these groups only ...
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### Kruskal–Wallis one-way analysis of variance is related to what kind of regression?

One-way anova is similar to regular linear regression because both use the F-test which involves sums of squares among other reasons. Is Kruskal–Wallis one-way analysis of variance similar to some ...
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### Non-normal data: lower p-value from Kruskal-Wallis than ANOVA

I am currently working with data in which I have one continuous variable (speed) and a categorical variable (3 different populations, with n ranging from 13 to 30 for each group). I have determined ...
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### Kruskal-Wallis test for multiple variables different in R and python [closed]

My dataset has one athlete per observation, and each column is the points he obtained in each category. I want to test if the medians for all the categories (so, the median of each column) are the ...
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### How does scipy's Kruskal-Wallis compute its H-value?

My textbook states the following formula to calculate the H-value of the Kruskal-Wallis test (without tie ranks): Let's use this formula to compute H for a really simple example dataset: group 1 ...
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### Interpreting residual plots for heteroscedasticity

I am trying to measure the effect of different antibiotics on the growth of E. coli and S.aureus. Since my data for both bacteria is not normal I have chosen to do a Kruskal–Wallis test. But one of ...
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### When doing FDR correction in graphpad prism after Kruskal-Wallis does the programme automatically perform a Dunn test?

I used the Benjamini-Hochberg FDR correction in graphad after performing a Kruskal-Wallis test. This gives me a list of individual P-values. The graphad website says that if you select the FDR ...
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### How to interpret Dunn's test in R (holm method)

0 1 I want to compare atmospheric pollutants concentrations between 3 geographical zones for a project. I used the non parametric test of Kruskal-Wallis, which returned a p-value<0,05, so I ...
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### Test for non-normal data with homogeneity of variance

I'm new to the platform and would like the following question to be answered: I have performed a latent class cluster analysis with 28 variables and 9000 observations, for which I am currently ...
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### How to test for a statistically significant difference between multiple unbalanced groups

I have 4 groups that are not normally distributed. I would like to know if they are significantly different, with the aim of knowing if they would make a good feature to base a classification on. I'...
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### Literature on nonparametric contrasts

I am wondering how I can perform and interpret contrasts in a particular case described below. I am comparing three independent groups which are not normally distributed (heavily), thus I have opted ...
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### Data analysis method for 1 independent variable and several dependent variables?

I am working on a fertilizer experiment, involving three different treatments of fertilizer. I wish to evaluate the relationship between the treatments (independent variables) with several different ...
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### Kruskal Wallis test gives significance, multiple comparision table doesn't

I'm comparing physico-chemical properties of 8 different kefir samples like viscosity at different storage times. I have 4 viscosity measurements for each group. When I conduct Kruskal Wallis test; ...
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### Why does the Kruskal Wallis test shows a difference but Wilcoxon doesn't find any between the groups?

Why does the Kruskal Wallis test shows a difference but Wilcoxon doesn´t find any between the groups, even tough the rank medians which are tested as far as I know look very different, and Dunn test ...
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### What is the best approach for testing for differences in independent variables across categories if samples are non-independent?

Essentially what I have are rasters, each with the same total number of pixels (N), represented by four categories that also have 12 independent continuous variables associated with each pixel. ...
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### Non-significant Kruskal-Wallis and significant post hoc tests

I have done this analysis where in Figure A-D. the Kruskal-Wallis global p-value is non-significant, but the p-value for pair CS and SCS in Figure A however is significant (at P<0.05). I read ...
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### Eta-squared from Kruskal-Wallis in R

Is it possible to calculate Eta-squared from Kruskal-Wallis test results? I know how to do it by hand for the ANOVA or Mann-Whitney using the Z-statistics, but i must use the KW test for my current ...
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### Kruskal-Wallis test for Length vs Year test

I have a dataset of the lengths of a species which has a 1-year lifespan, going back 20 years. I would like to test if the lengths recorded each year are significantly different from one another (for ...
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### Is Kruskall-Wallis H test suitable to influence marketing plan after survey?

I've run a survey which received around 270 responses from a population of around 5,500. The survey asks brief demographic questions followed by opinion questions, akin to the following: Demog Q 1: ...
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### What test is the most appropriate in this design with multiple variables?

I have a test design in which I have 1 base condition and around 14 test conditions. Each of those 15 conditions has a total of 15 observation points (so equal sample size). The base condition ...
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### Advise for two non gaussian distribution group

I have a dataset which test the introduction of a new measure of a luggage checking a local small airport, the aim is to conclude whether the new measure reduce the luggage checking time. My dataset ...
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### How to interpret the kruskal wallis test in r

I am trying to understand the results on the kruskal wallis test that are produced in R. The data that I am testing: ...
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### In scipy why stats.kruskal can work with two populations?

Krustall-wallis testing should be working only at least with 3 populations.But here, it seems to accept 2. Krustall-wallis extends the Mann–Whitney U test, which is used for comparing only two groups....
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### Is Serial Independence, an assumption in Friedman and Kruskal Wallis Tests

I understand that Friedman and Kruskal Wallis are non-parametric tests to see if different groups come from same population. I also gather from here that these tests are used to test for seasonality....
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### Can Kruskal-Wallis test be used in groups of different size?

I am trying to compare Likert-scale answers to a survey applied in 3 different cities: A, B and C. I arbitrarily chose twice as many respondents from A, for a total of 500 answered questionnaires in ...
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### What to do when assumptions of both ANOVA and Kruskal-Wallis are violated?

I am trying to analyse whether three groups (samples sizes 27, 26 and 23) differ in their responses to 20 questionnaire items, each measured using a 5-point likert scale. The items are all ...
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### Can I use multiple regression on a ranked response variable as a significance test for multiple covariates?

This blog post illustrates the relationship between inference tests on groups (t-test, ANOVA, etc.) and equivalent linear models. It also claims that for reasonable sample size, regression of a ranked ...
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### What is exactly the non-normality requisite for nonparametric tests? [duplicate]

As the title says, what is exactly what is being tested before deciding to use a non-parametric alternative test (as Kruskal-Wallis for ANOVA, or Mann-Whitney's U for student's t)? Most sources are ...
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### Why several studies change logical paired/unpaired assumption from omnibus to post-hoc?

There are several studies of highly-referenced researchers where a paired post-hoc test (e.g. Wilcoxon signed-rank) follows the omnibus unpaired test (e.g. Kruskal-Wallis): From Huang et. al "THE ...
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### Can I use UNPAIRED post-hoc analysis for PAIRED omnibus testing?

If I have a omnibus statistical test with unpaired assumption (e.g.Kruskall-Wallis), could I ever use the opposite (paired) post-hoc analysis? (e.g. Wilcoxon signed-rank for post-hoc analysis of ...
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### Statistical Analysis of 3 groups(parameterisation of same algorithm) under the same dataset: non-repeated measures or repeated-measures?

I'm analyzing the performance of 3 parameterizations of the same algorithm under the same dataset. This performance is user-evaluated under a single Likert-type item (5-values). Given the ordinal ...
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### is Kruskal- Wallis test appropriate in this case?

Does this make sense, is this test appropriate in order to see how responses differ among more then 2 different groups? I have no experience working with SPSS. Is there any chance someone can help me ...
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### Kruskal-Wallis and Negative binomial regression do not agree

I am comparing the number of broods made by dung beetles (Brood_Number) across three temperature treatments (Temp_Offset, a 3 ...
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### Multivariate test for likert scale data in r programming

I have a data of likert scale type, collected to know the 'level of awareness of individuals' about various investment options. I want to check if there is significant difference in level of ...
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### Effect size calculation for Kruskal-Wallis mean rank test

I have a published paper in which I'm attempting to calculate the effect sizes for various outcomes. For a pre-post scale, the authors report the sample size, mean rank, and p-value for an outcome (...
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### Comparing heteroscedastic groups with sample sizes from 1 to 24… No valid tests?

I'm comparing 1 continuous variable across 36 groups (nurses grouped into 36 hospital units). Several groups have only 1 observation, but most have more, ranging from 1-24 observations per group. ...
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### Small sample size ANOVA

I am working with monthly results of some variables, and I would linke to compare weather 6 years are statistically different or not, so my saple size per group (year) is bounded by 12. I ran Shapiro ...
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### Independent or matched groups?

A very beginner level question here: I'm trying to see whether there is a difference in how students assess the usefulness of 5 possible courses to be added to their curriculum. Each student was asked ...
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### Kruskal–Wallis vs Mann–Whitney when comparing pairs

I am wondering the following. Given a dataset of measurements of one sample under 7 different conditions, which test is the most accurate and appropriate to use when comparing each two of the ...
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### Is the ICC appropriate here?

I have N tissue samples, labelled as either A or B. 2 measurements are taken from each sample. The data is not normally distributed. I'm interested in 2 things: firstly, whether there is ...
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### Post hoc for Levene test

I have a problem regarding my data analysis. One of my hypothesis is basically that my groups will differ in terms of spread of the scores, indicating that there would be a difference in extremity ...
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### What is the appropriate test when dependent variable is ordinal binary and independent variable is continuous?

I am curious what is the most appropriate test to use when the outcome variable is an ordinal binary (test score of pass or fail) with a set of four unordered treatment conditions (A,B,C,D) as the ...
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### Weighted Kruskal-Wallis Test and Questions

I am currently studying the prevalence of a particular disease among eight different subgroups (for example, the prevalence of hepatitis B among HIV+ patients, HIV- patients, etc.). Each subgroup ...