multiple pair wise nonparametric comparisons
is it possible to perform multiple pair wise nonparametric comparisons (generally using a Mann–Whitney test) and adjust the significance level used for the decision criteria using a Bonferroni-type...
View ArticleMann-Whitney U test and paired data
I’ve read that working with paired data requires other method than Mann-Whitney $U$ test. I am not sure about how formally accurate is this statement. Reasons: Suppose that there is a set of $n$ (for a...
View ArticleTesting data for Same Shape
I want to run a Mann-Whitney test on 2 arbitrary sets of data but I read that one of the assumptions of the Mann-Whitney test is that the data is the same shape. How can I test if the 2 sets of data...
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Which test to use: Mann-Whithney U or Spearmans rho or both?
I have the following question: I have a sample group, which is divided in to two subgroups: “good” and “bad” people. I have their points achieved in an IQ test. Points are grouped into 4 categories...
View ArticleComparing Peptide Amino Acid Composition: 2 Independent groups, Non-normal...
I have two large groups of peptides, “positive” group (n = 368) and “negative” group (n = 880). The average length of the peptides (in each group) is about 20 amino acids. What I am trying to do is...
View ArticleRelationship between ROC curve and statistical significance in comparison of...
My question is about any possible relationship between the significance of a comparison test (Mann-Whitney U) and the ROC curve. If the comparison test is strongly significant, should we expect a...
View ArticleInterpreting contradicting results T-Test vs. Mann-Whitney test (2...
I want to test if two indepent experimental groups are sign. different in terms of one outcome variable, but face the following questions: Basic setup 2 groups with 200 observations each Outcome...
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Why I receive a n/a sign with a Wilcoxon rank-sum test calcualtor? [on hold]
I was wondering why I receive a n/a sign with a Wilcoxon rank-sum test calcualtor. I used a calculator find from internet but I cannot understand the n/a interpretation. Here is a screenshot: Does...
View ArticleMultiple comparisons when preforming a t-test and Mann-Whitney U test
I have 90 proteins(column) and about 170 samples(rows) with data. The data describes protein levels for 90 different proteins. Every samples is also in a group, A and B. I would like to preform a...
View ArticleHow to interpret Mann-Whitney's statistical significance if median is equal?
Testing the difference between the observations of two groups by using Mann-Whitney Test has given the following output (from minitab): N Median positives 137 1.0000 negatives 892 1.0000 Point estimate...
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