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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How to interprete when data is statistically significant with longitudinal mixed effects but not Kruskal Wallis/Welch Anova?

I have a repeated measures experiment with each case being measured at 3-4 timepoints. The cases are grouped into three groups. When I analyze the measures within each timepoint e.g. timepoint 1, ...
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Comparing differences between three or more unpaired groups (DV categorical and non-normal continuous) and describing used tests

I have a made-up table as follows, including a footnote describing given p-values. P-value shows the differences between all subgroups, and it was derived from the Kruskal-Wallis test for continuous ...
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Should I use a parametric test or non-parametric test?

I'm analysing a set of data on the fluorescence intensity of a particular receptor. All the data are in the form of a fraction as they are being compared to a control. ie. fraction = intensity of test ...
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What is a good location equivalence test for comparison of small and large samples?

I have two one-dimensional samples, one is small (like 2 values) and another of a larger size (several dozens). I want to estimate the probability that the two samples are drawn from different ...
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Kruskal-Wallis and Wilcoxon test with means and sd, Monte Carlo

I know this is unorthodox question. I have a software which runs Monte-Carlo simulations and outputs means, SD, SEM. I wonder if I can use these results from different distributions to carry out ...
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Kruskal-Wallis post-hoc analysis [duplicate]

I am doing a Kruskal-wallis test and am wondering which post-hoc analysis is the most suitable for this? Been reading around and saw people recommend Dunn test. I am just wondering if there is any ...
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Need to test heteroscedasticity before using the Kruskal-Wallis test

My question is whether or not I have to test heterodasticity before using the Kruskal-Wallis test. What I understand is that if I want to compare medians, then I have to check for heteroscedasticity, ...
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Multiple comparison correction for Kruskal-Wallis test with multiple dependent variables

I want to compare 3 groups on 10 dependent variables. I plan to use Kruskall-Wallis test with post-hoc comparisons. What kind of correction shoud I use at each step? For one DV it is obvious - I ...
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Test for Nominal Response Vs Continuous Predictors? (R)

I cannot find much information on this, none so-far useful. I have a sparse data set with 17K+ columns of continuous gene expressions, an example of a typical column: (3.15, 0, 7.1294, 0, 0, 0, 2300.2,...
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What kind of ANOVA is appropriate for a single grouping with correlated measurements?

Lets say I have a bunch of meteorologists who all attempt, at the start of each day, to estimate the max temperature that will be observed for the day, for a whole bunch of weather stations dispersed ...
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Can I use Kruskal Wallis test to analyze ranked data? If not, what analysis method should I use?

I am currently conducting a survey study for a project. Unfortunately, I would not at all consider myself proficient in statistics, and am struggling with choosing the appropriate analysis method for ...
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Is there a way to calculate the magnitude of the difference in means in R?

I have a dataset with a non-Gaussian distribution - signalment and body measurements of three species of bird. I have used the Kruskal-Wallis with post-hoc Dunn Test and Bonferroni correction tests to ...
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Statistical test appropriate for comparing frequencies between groups

I have a table with frequencies of a gene inheritance between two groups as shown below: Genus Paternal Maternal Bi A 260 40 50 B 5 30 25 I want to test whether (i) frequencies among the ...
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Are the data grouped by different drug doses graded data or disordered data?

I have a set of data, the structure is as follows: 5mg 10mg 15mg 20mg Survive 15 22 18 24 death 3 2 3 2 I divided the patients into 4 ...
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Visualising significance of difference between nominal groups

I have a data set that gives the number of issues found during annual vehicle inspection for various car models and it probably is a vague requirement but I need to come up with a way to visualise ...
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Multi-Factor Kruskal Wallis Test in R

I have a dataset where the response variable is a non-normally distributed proportion and is heterogenous with respect to all factors. I cannot seem to transform the response variable into anything ...
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Comparison of medians in data with multimodal distributions

I'm comparing continuous data obtained at two different time periods with the distributions seen below. They appear fairly similar, but they're clearly non-normal. The ideal hypothesis is that the ...
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1answer
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Testing for difference in distributions of Likert-scale data that differs only in a median-preserving spread

Assume that I have a Likert scale with five categories, coded as {1, 2, 3, 4, 5} and that I have two samples, the first of which is generated by drawing from a uniform distribution over these five ...
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Kruskal-Wallis Test effect size: Can it be greater than 1?

The Kruskal-Wallis Test effect size can be calculated based on the formulae from the article, once the Kruskal-Wallis H-test has been computed, the epsilon-squared estimate of effect size can be ...
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Kruskal Wallis test for two samples returns error in a particular month

I am performing the Kruskal Wallis test in R to check the similarity/differences between samples in 6 pairs; each pair has two samples. Just to be clear, the pairs are not being compared to each other....
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Testing equality of variances in very small samples

If I have two very small samples with i.e. 3 or 4 observations and I would like to check if their variances are significantly different from each other. However, when I want to apply the Kruskal- ...
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Calculate power of the Kruskal-walis test [duplicate]

I think this has been asked before on here but it didn't get a straight answer. I would prefer to do it in R if possible.
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190 views

Can Kruskal-Wallis be used for discrete data?

I have a data frame with variables that are counts, nominal (two groups) and continuous. Two of the continuous variable follow a normal distribution; the counts variables do not follow a normal ...
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Comparison of property of 5 treatments with just 4 observations each

I have a small dataset with 4 observations per treatment. My plan was to do an ANOVA, so I checked the response variable for normal distribution with Shapiro-Wilk for each treatment and there was one ...
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NA values when converting into wide format for Wilcox's robust ANOVA

I have a dataset of more than 10.000 values, with 12 different factor levels that are NOT evenly distributed. For my dataset, Levene's test is very significant which means that the assumption of ...
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What statistical test to perform to find differences between groups that has sub-groups?

I have this dataset (N = 15k) in which there are 17 main variables and 8 topics. The variables are all continuous while all topics are binary. Data ...
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1answer
43 views

Kruskal-Wallis and Mann-Whitney U give different results

For my thesis, I am comparing the importance of "comfort" (measured using a 6-point Likert scale) among four groups of people (participants who prefer traveling by plane, by train, by coach ...
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Can we do a Spearman's corelation between a continuous and an categorical ordered variable (0,1,2,4)?

just a question that may be already answered here, is it possible to perform a Spearman's rank correlation ( to find a correlation) between a continuous variable and a categorical ( ordered) variable ...
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Finding meaningful boundaries between two continuous variables in R

To find the relationship between two columns of the iris dataset, I am performing kruskal.test and p.value shows a meaningful relationship between these two columns. ...
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67 views

What does offsets mean in reference to expectations in R package MultNonParam?

I am trying to calculate sample size for Kruskal-Wallis test using kwsamplesize included with the MultNonParam R pacakge https://cran.r-project.org/web/packages/MultNonParam/MultNonParam.pdf. The ...
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1answer
33 views

Correcting for multiple kruskal wallis tests

I am running a kruskal wallis test a number of times (37) and wanted to know if I have to adjust the p-values of the kruskal tests before I look any further into the post hocs?
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When to correct for multiple kruskal tests? [duplicate]

I am running multiple (37) Kruskal wallis tests to check if there is a difference between three disease groups. I do this using groupby in R to group all the 37 ...
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81 views

Change over time between two groups and within groups - Mann Whitney or Kruskal Wallis?

I have two groups (Control and Disease) and for each group a variable y is measured at three time points (0H, 24H, 48H). I want to know two things: Does y change between Control and Disease at each ...
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70 views

Choosing the right test to compare the difference in mean between 3+groups according to the data we have (param vs non-param, sample size..) [closed]

I hope everyone who reads this is fine. I come to you for help, I am a student in data analysis, but I am not yet familiar with everything, especially regarding tests. I have 3 groups of independent ...
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32 views

What statistical test should be used to compare groups when the assumption of independence is violated?

I would like to test if there are statistically significant differences between three groups (defined by an outcome measurement) for some categorical and continous variables, respectively. Normality ...
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281 views

Kruskal-Wallis test allowing for one covariate?

As a non-statistician (I am human geographer, interested in health geography), I am trying to solve a problem (using R). Let's say I have a simplified database called df which contain these variables: ...
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268 views

Interpretation of Kruskal Wallis post-hoc pairwise comparisons - SPSS

I've run a KW test on my set on non-parametric data in SPSS, the output of the test giving me a p-value <0.05. As I have 20+ groups in my data set, I'm interested to see which group significantly ...
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26 views

Equivalence of Kruskal-Wallis and Spearman's correlation test

When fiddling around with the Kruskal-Wallis test and Spearman's rank correlation test I noticed that both test have the exact same ROC curves in some simulations I'm running. In each round of ...
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23 views

Compare dependent categories over time?

I have a dataset with 50 individuals. 25 are exposed to a substance on low concentration, 25 are exposed to a substance on high concentration over time. I have 4 categories that represent different ...
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1answer
45 views

Have I presented Kruskal-Wallis test properly?

For the second part of my paper I collected data on whether patients' condition was acute/chronic/unknown and also collected their opinion to a statement Y on a likert scale I want to compare whether ...
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61 views

Best way to look at this data, non-linear model, linear model, ANOVA (Tukey post-hoc) or Kruskal-Wallis (Dunn post-hoc)?

So I have collected data, it is the fresh-weight of tomato plants in mg. over a series of 3 timepoints (4 days, 7 days and 10 days), comparing 6 different treatments (6 treatments are comprised of &...
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1answer
24 views

Kruskal-Wallis test describing data

If I carry out a Kruskal Wallis test and the result comes out as significant, how do I then go about describing those differences and also which groups the difference is present between? For example ...
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1answer
38 views

How to get the standardized z-statistic from dunn.test-package in R?

Sorry if this is a trivial question, but I couldn't find anything on it. I am running a Dunn-test with the dunn.test-package: ...
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Testing for difference in sums between multiple groups

Let's say I have two stores, A and B, and within a span of one day the total number of clients to purchase from these stores is $N_A=100$ and $N_B=30$ respectively. For each store I recorded the ...
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1answer
855 views

Likert scale questionnaires with ANOVA and Kruskal-Wallis test

Could someone recommend me sources where I could find illustrated examples, solved by hand and/or using software, on how a Likert scale questionnaire (with more than 1 question, say 10, 20, etc. ...
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Comparing means with unequal variances

I have a dataset (n = 451) of integers split into six uneven groups and was hoping to run a version of a one-way ANOVA to compare means, but I'm struggling with meeting the normality and equal ...
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1answer
26 views

Kruskal-Wallis rank sum test for two-level dependent ordinal variable

Hello I've been reading multiple references regarding the use Kruskal-Wallis rank sum test for ordinal variables, but none explicitly mentioned or cautioned against using this to a dependent variable ...
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Opinions on a statistical error in p values (re: standard deviations, t-test/Kruskal-Wallis) in a published study? [closed]

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 less than about 30 ...
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1answer
91 views

How do I report median after running the Kruskal-Wallis Test?

I am evaluating the levels of thyroid hormones and thyroid antibodies in 3 groups namely: pre-eclamptic pregnant women, non-pre-eclamptic pregnant women, and apparently healthy non-pregnant women. ...
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2answers
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Analysis of variance for nonnormal data with unequal variance

I would like to ask whether it is possible to perform an analysis of variance on data that is not normally distributed and has unequal variance, but I have large enough sample size. I have read that ...

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