Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [friedman-test]

A non-parametric test for the equality of >2 dependent groups.

Friedman's test is a non-parametric test for the equality of more than two dependent groups.

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Friedman test and post-hoc test for Python

In my dataset, I have five (ordinal) groups with an x-amount of measurement. Because homoscedasticity is violated, I performed the Friedman chi-square test to see if there are any statistical differences between the groups: fried =…
Robin Kramer
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Friedman's test is very significant, but its post hoc comparisons (SPSS) are not significant

I ran a non-parametric Friedman's test for my data in SPSS 22 and significantly rejected the null. That would mean that among the $k$ paired samples (3 in my case), there should be detected at least two samples with unequal distributions – one…
Niksr
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Non-parametric test for repeated measures and post-hoc single comparisons in R?

Some attribute $x$ of 17 individuals was recorded repeatedly on 6 time points using a Likert scale with 7 distractors. Which statistical test(s) can I apply to check whether the changes along the 6 time points were significant? set.seed( 123 ) x <-…
saschaview
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All vs all post-hoc after Aligned Friedman (k classifiers over multiple datasets)

I have k classifiers and n datasets, and I have only one accuracy measurement (which is actually the average of three independent repetitions of the 5-fold-CV, i.e. average over 15 accuracy values) for each algorithm+dataset combination. I have read…
Pablo
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What is the right Bonferroni adjustment?

I am trying to test a hypothesis for my Masters Thesis. There are 3 conditions (I will name them X, Y, Z), in each of which the data isn't normally distributed, and measures the improvement for each condition. I ran a Friedman test as a repeated…
Izzy
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How to interpret the result of Friedman's test?

I uploaded the data and then I used bootstrapping to have 10 different samples from the original data but with the same length as the original data. For each sample, I used 7 distance metrics, and I calculated accuracy and other performance…
jeza
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Can Friedman's test be used with two samples?

When talking about Friedman's test, it commonly comes accompanied by a whole name of "The Friedman's test for three or more correlated samples". The question is, could results be valid if I apply the Friedman's test to two correlated samples? Or is…
User2130
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Equivalence of formulations for Friedman Test?

I'm trying to implement a Friedman test, and came across two sites giving methods for its implementation, namely, Wikipedia (perma-linking for posterity) and the NIST. At first glance, the general setup of the methods listed appears the same --…
MichaelChirico
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Friedman? Unequal samples sizes

my students were involved in three different simulations. I was asked them to rate their satisfaction with these simulations on a 5-point Likert scale (several items). Unfortunately, I have 60 questionnaires for the first simulation, 57 for the…
Lena
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Is there a two-way Friedman's test?

I have ranked concentrations (from 0 to 5) of 5 different proteins from 3 different locations from the same patient. In total, 15 measures per patient and 61 patients, so 915 observations. What I'd like to know is if: The 3 locations are the same…
Saccharo
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Non-parametric, repeated measures two-sample test with small sample size

My data consists in two samples relative to the expression of a given gene, with 4 replications in both samples. I am interested in testing whether the two samples come from the same population, taking into account the fact that I have repeated…
Stefano Lombardi
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Post-hoc Friedman Nemenyi Test

I used Friedman and Post-hoc Friedman Nemenyi Test. In this PAPER, page 11, the Critical Difference (CD) equation is different from what has been used in R function, PAGE 14 posthoc.friedman.nemenyi.test. The only difference is that in R function…
jeza
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Which within-subject non-parametric test?

I have to do a non-parametric test on data because the distribution is not normal. The data is about the effectiveness of 2 different Aphasia therapies. There are 54 Aphasia patients tested before any treatment, after treatment type A and after…
user137130
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Is my data ordinal?

I am comparing three groups of participants, who gave ratings during a certain test on a scale from $1$ to $4$ (with $0.25$ steps). I was planning to do an ANOVA, but realized that a thing such as the mean of ratings $1$, $2$, $2$ is $5/3$ and does…
annie
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Why run a post hoc wilcoxon signed rank test after Friedman test, why not just skip to Wilcoxon sign test instead?

I understand that one is required to run post hoc tests after the Friedman test. For example, while the Friedman test may find a statistically significant change amongst 3 treatments, one may follow with Wilcoxon signed rank tests to find where that…
user6306773
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