Questions tagged [wilcoxon-mann-whitney-test]
The Wilcoxon rank sum test, also known as Mann-Whitney U test, is a non-parametric rank test to assess whether one of two samples has larger values than the other.
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Is $F_X(t) > F_Y(t)$ a sufficient and necessary condition of $\mathbb{P}(X < Y) > 0.5$
I asked the question when conducting Mann–Whitney U test using the scipy implementation. The null hypothesis for one of the one-sided tests is $F_X(t) > F_Y(t)$, where $F$ denotes a CDF. I wonder ...
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Rank correlations: what is the difference between spearman coefficient and $R^2$? [closed]
When the data are not normal, how can the Spearman rank coefficient be interpreted differently from $R^2$?
As I understand it, when performing a rank correlation, the axes typically shouldn't show the ...
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Best test for mortality rate in two countries
We’re trying to compare the mortality rate in two different countries over a period of 20 years. Is the Mann Whitney u test the best to use? We’re confused if the data is assumed to be normally ...
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Unbiasedness Wilcoxon-Mann-Whitney Test
There are many different alternatives discussed for the Wilcoxon-Mann-Whitney test. One alternative is $P(X < Y) + \frac{1}{2}P(X = Y) \neq 0.5$. There are compelling arguments for this, such as ...
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Am I Doing Things Right? / negative binomial test
I have a dataset consisting of social media comments about a particular context from 1999 to 2024.The topic titles of the comments were annotated into two categorial variables = 0 and 1.
I am aiming ...
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Mann-Whitney U Test for ranked data when there are only 4 ranks
During my university lecture I was told that for Mann-Whitney U Test on ranked data, the scale must have at least 5 different values (ranks). However, I am not able to find this information online so ...
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Can the One-Sided Mann-Whitney U Test Have a Composite Null Hypothesis?
Let's say there's an i.i.d. sample $X_1, X_2, \ldots, X_{n_1}$ from a distribution with the CDF $F$ and $Y_1, Y_2, \ldots, Y_n$ from a distribution whose CDF is $G$.
As far as I know, the null ...
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what is the meaning of “One-sample test.”？The following is clearly a two-sample test for wilcox.test
The code that inspired this question can be found here and below:
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Is Kruskal-Wallis really a good test of stochastic superiority?
After much reading/googling, I reached the conclusion that the Kruskal-Wallis test (K-W) is a test of stochastic superiority (or, equivalently, of stochastic equivalence). Rejecting the null implies ...
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What does it mean for a variable to be statistically significant but not selected as important by classification methods?
I'm basically playing around with some lipidomics data to practice, so my question is purely theoretical.
I wanted to see if I could find lipid classes that differ between two groups and I was ...
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Unexpected p-value distribution of Mann-Whitney U test under null hypothesis
I am getting very unexpected results of p-value distribution of Mann-Whitney U test under null hypothesis.
I am working on a real data, but I was able to replicate the results on artificial data with ...
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Appropriate test to prove hypothesis for given sample
Essentially, I'm writing a research paper, and I have these subjects grouped by their cancer stage from I to IV (ordinal scale) and whether or on they're positive for a specific marker (nominal scale)....
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How to compare semi-independent groups?
I need to compare the answers to a questionnaire (pre / post). The questionnaire was designed using a Likert scale. The two groups were made up of populations, some of whom were in both groups but ...
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comparing two matrices with wilcoxon test
I have two matrices A and B of 2388 rows and 1001 columns. I would compare two matrices with wilcox.test but is not clear to me if I had:
directly input them ->
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What is the correct way to perform one sample paired wilcoxon test?
for simplicity, let's say I have a dataframe called df, with two variables - weight_0 and weight_1.
weight_0 describes the weight of participants before intervention, and weight_1 describes the weight ...
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