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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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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1answer
73 views

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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1answer
37 views

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 ...
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Dunn's test: is it appropriate to use p-values to interpret relative between group similarity

For a set of data that I collected, I used the Kruskal-Wallace test to determine whether there were between-group differences in the parameter I measured. It returned a significant result, so in order ...
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Appropriate analysis for univariate proportion data and environmental variables

I'm new to statistics so am trying to choose the best analysis to find if; There is a difference between canopy cover (0-100%) at different sites There is a relationship between canopy cover and ...
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Friedman and Kruskal

I have a data with 4 groups and multiple variables with measured values. my groups are ES, EP, PP and PS. ES and EP are associated and PP and PS are too. So i would like to compare my groups in non ...
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What test do I use for this? (NOOB biostatistics question)

Suppose I have some subjects and I give each of them a test. I would end up with a dataset like: ...
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Mann-Whitney (2 groups) contradicted by Kruskal-Wallis (3 groups)

We have two groups that are significantly different (tested with Mann-Whitney). When a third group is added, the Kruskal-Wallis tests provides a non-significant result. This implies that two or more ...
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Is this a valid approach to hypothesis testing

I have been a machine learning hobbyist for a while now and am attempting to formalise my understanding of the statistical foundations to data analysis and machine learning. My reading so far has ...
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Comparing means in large samples: effect size and p-value

I have a large sample (10000+ per location) of temperature measurements which I would like to compare between 3 locations. I'm checking if there is a significant difference in temperture means between ...
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Which statistical test for my data?

(EDIT: question simplified) This is a basic question, since I am new to data analysis and statistics. I am carrying out a 2X3 factorial survey where participants are presented with a series of ...
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136 views

Is it correct that JMP has Mann-Whitney U for comparing more than 2 unpaired groups (instead of Kruskal-Wallis)?

To the best of my knowledge, the Mann-Whitney U test (also called Wilcoxon-Mann-Whitney) is for comparing only two unpaired groups, while the Kruskal-Wallis test is used for comparing two or more ...
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What is the point of a permutation F-test when all you need is one F-test for one-way ANOVA?

Say you have three groups, and each group has 5 observations. You can figure out if there is a significant difference between means with a simple one-way ANOVA. I read in my nonparametric book, one ...
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Normality vs normality of residuals

I am currently trying to perform a hypothesis test on the difference between four means. Initially I was trying to use ANOVA but then realised I may not meet the assumptions for this test and may need ...
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Reporting insignificant results using mean ranks

I have a number of non-significant results from a Kruskal-Wallis test and wondering the best way to report them. My independent variable is 3 categories: Group A: Uses product A; Group B: Uses ...
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Statistical test to use to test mean equality given non-independence assumptions

In a survey conducted, 75 survey participants were asked to rate randomized keywords from groups 1-5. Every keyword belongs to a group and subjects were asked to rate each keyword. I would like to ...
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59 views

Kruskal Wallis test or Friedman for multiple preselected unmatched pairs

I am unsure whether I should use Kruskal Wallis test or Friedman's test in the following case, where I am required to use a non-parametric test while compensating for multiple comparison with a post ...
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How to test for differences between groups for ordinal outcome variables in SPSS?

I do not have experience with ordinal data, please help me out with my questions? I have conducted a survey which consists of 25 Likert-items, these items are all statements for certain conditions ...
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1answer
146 views

How can I calculate confidence intervals for epsilon-squared (Effect size for Kruskal-Wallis test) in R? [closed]

I'd like to calculate the confidence intervals for the epsilon-squared effect size statistic in R. Here is the code I'm using to calculate the epsilon-squared value: ...
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Should ANOVA be used when the dependent variable is an integer, such as a count of items? [duplicate]

I have data for a dependent variable, DV, representing a count of objects, with a range from 0 to 6 (sample size 450), slightly left skewed with a mode at 4: Furthermore, I have a single categorical ...
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Comparing 3 groups at 2 time periods

I'm analysing a dataset and comparing three zones at two points in time. The data in question is: Hourly sightings of wild fish (CPUE) In one of three adjacent zones (A, B, and C) During the ...
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Mann-Whitney U test or Kruskal Wallis test for comparing median of two groups?

I know that Kruskal Wallis test can be used to compare median of two or more groups (e.g. see this link: https://www.statisticshowto.datasciencecentral.com/kruskal-wallis/ ), and that Mann-Whitney U ...
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Using Multiple Comparisons for Kruskal Wallis Follow up analysis

I am performing the Kruskal Wallis test on ~100 samples and wish to group statistically ‘similar’ samples together. The method I am using is described in Andy Field’s ...
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24 views

Pair-wise ANOVA or non-parametric comparison

I'm doing an experiment with 7 groups (batches) of 12 measurements of a certain chemical, where one group (b0) is considered the baseline case. The research question is to find out which groups have ...
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Meaning of chi-squared in R Kruskal-Wallis test

I have a simple question to ask, I think it was not covered in other questions. I am running a Kruskal-Wallis test in R, using the function kruskal.test. The output gives me the p-value and a chi-...
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63 views

Non-parametric test for interaction effect

I have a relatively small data set with quality ratings (dependent var), for different compression methods (independent var 1) applied to different types of video (independent var 2). My first ...
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193 views

ANOVA with post hoc for non-normal data with unequal variance

I have 200-some variables with 25,000 observations in each of 4 categories. For each variable individually, I need to identify where we have variability between categories. Therefore, I need an ...
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Is my analysis approach and decision valid?

I'm busy with a class assignment and I would appreciate a second pair of eyes on my analysis approach. A part of me feels that I'm overthinking this or have done an unnecessary test. Context: Use 4 ...
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Find joint distribution for two different cases Kruskal Wallis

I'm a bit stuck with my homework in a subject called "Non-parametric Statistics". The task is related to Kruskal-Wallis test. The task is as follows: Let's look at the comparison of 3 independent ...
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Can I use both parametric and non-parametric tests?

I have 3 variables, A1, A2 and A3 A1 is temperature A2 is month A3 is location A2 has 2 months - March and May. A3 has 2 cities - Chennai and Dubai. My data is ...