Questions tagged [wilcoxon-signed-rank]

Wilcoxon signed-rank test is a non-parametric rank test to compare two paired samples, whether values in one are bigger than in the other. Can also be used to compare one sample to a fixed value. [The test NOT to be confused with the `sign-test`].

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One-Sample Wilcoxon Signed Rank Test when the values are identical

I'm trying to run One-Sample Wilcoxon Signed Rank Test on my data. My data contains 100 values, and I want to compare these values to a standard value. However, all the 100 values and the standard ...
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Using an old trained model on a new data - comparing two populations

I have two populations with the same set of features. The range of the features' values is also the same. I trained Random Forest Algorithm on the first population. Thus, I wonder whether or not I can ...
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One Sample Wilcoxon signed-rank with a negative effect size

Hi i got a Wilcoxon signed-rank done for a one sample t-test because the data failed normality tests. Whilst the result is still significant, the effect size is -0.364. Apparantely it uses the '...
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Comparing similarity of samples under time-dependant noise (KS-test for dependant samples)

I'm measuring response times of a process under different inputs and want to check if the input correlates with the response time. The problem is that the differences I'm expecting are small while ...
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Is a Wilcoxon paired test correct for my case?

We're working with the lovely garden eels: snake-like fishes that live in big colonies, attached to the sandy sea bottom. They feed on plankton and hide in their burrows whenever something big ...
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Test statistics for hypothesis that values in one group always larger than the other group

Assume $x_1, x_2, \dots, x_n$ belong to group $A$ and $y_1, y_2, \dots, y_m$ belong to group $B$. We want to test if values in group $A$ are smaller than values in group $B$ as values in B. I design ...
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Too small sample size for Wilcoxon signed rank test, alternatives?

I have a statistical question about my research. I performed photosynthesis measurements on leaves. I have 6 increasing light intensities, and for every light intensity, I measured the photosynthetic ...
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Student's t-test versus Wilcoxon signed-rank test

Trying to understand when to use which test, am I correct when saying both these tests, test whether two samples could be taken from the same distribution, but the difference is that the student's t-...
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One-sample Wilcoxon test result does not make sense

To evaluate the correctness of a value I have given to something, I have asked a group of people to give a value for it. To evaluate the significance difference between my value with them, I am ...
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Is it appropriate to estimate the mean difference from a Wilcoxon p-value?

I am conducting a meta-analysis involving paired data (two instruments measuring the same thing). Original papers do not provide the standard deviation of the mean difference. One paper provides a p-...
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One-sample versions of the signed rank and rank sum tests?

I wonder if there are applications of the signed rank and rank sum tests in a one-sample context? Signed rank Is there a form of the signed rank test where the difference $A-B$ for each subject is ...
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Can't decide between Paired t-test and Wilcoxon Signed-Rank test?

I'm using data for pre-2020 January-April and the year 2020 January-April (raw data with one datapoint per day, except for the 'pre-2020' category which is the values for one day in 2017, 2018, and ...
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What does it mean if Nemenyi test does not return that the performance of two methods are significantly different while the Wilcoxon test does?

I want to compare the performance of $N$ methods on $m$ datasets. I performed the Friedman test and after that the Nemenyi test. The Nemenyi test is though not powerful enough to conclude that there ...
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nonparametric tests for random forest regression

Ive built a random forest model which predicts temperature, humidity and energy based on 5 inputs. I obtain an R2 value of 0.92, CV(RMSE) of 14, and errors of 3.51%, 4.22%, 7.23% for each variable ...
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Can I use `wilcox_test()` to compar multiple means without `friedman_test()`?

In this example,use friedman_test() first to find significant difference between group,and then use ...
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Friedman test: non-significant post hoc (exact and Nemenyi test) should I run Wilcoxon signed rank tests or Sign tests? Or just accept the results…?

In my data, participants were tested on the same ordinal variable 3 times. In order to test for within-group differences, I ran a Friedman test. After reading this post, I ran the friedmanTest ...
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Wilcoxon Signed-Rank with unequal samples

My apologies if this is a novice question: I am using a 2 tailed Wilcoxon Signed-Rank test to determine if suspension days decrease following a year of PBIS implementation in a middle school. Sample: ...
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Is a statistically significant difference within analytical uncertainty still valid?

The isotopic analyses of two tissues across 50 specimens showed a mean difference of 0.12 ‰. A Wilcoxon signed-rank test for paired samples indicated this to be statistically significant (Z: -2.515, P ...
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Wilcoxon 2-sided test: rejection direction?

I am performing a Wilcoxon signed-rank test on some data, and I would like to show that my experiment A gives better scores than experiment B. I chose a two-sided test as I don't know if A > B or B > ...
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What test is appropriate test for confidence interval for proportion sample (R test)

Seeking appropriate R test approach for small sample. Given 160 units randomly sampled, 140 met the requirements approved living quarters by county standards. If we desire a 90% confidence interval ...
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Comparing two discrete paired datasets

The problem: I am studying the estimated number of cases of malaria in regions of the world and found that both the WHO and IHME have their own estimates. I want to find if the difference between the ...
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How to test right-skewed distribution hypothesis?

Statistics is new to me. My dataset has 7000 incidents that were processed within x number of days. I took a sample of 400 from the population: ...
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Wilcoxon signed rank test for likert data and composite scores

I have a survey where I used seven point Likert scale for all the questions. With 1 being Completely disagree to 7 meaning Completely agree. I wanted to combine multiple questions (let's say 7 of ...
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Non-parametric version of one sample t-test but for multiple groups?

Suppose I have the following experiment set up. I'm trying to build a regression model to predict how much weight a person can bicep curl based on their bicep size. So I go ahead and have a bunch of ...
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Paired t-test on large sample that *should* be normal, but isn't (or Wilcoxon Signed Rank Test)?

A dataset contains the number of fast food restaurants per thousand people for each county in the USA, for two different years (five years apart). 3,143 rows. None of the following are normally ...
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Alternative test

I am doing a peer review. The article is about the effect of yokukansan (YKS) on behavioral and psychological symptoms of Alzheimer disease. There were 15 patients, divided into 2 groups: the ...
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Statistical test for repeated measure data (3x2 contingency table)

This is my dataset Newspaper Internet MN 45 115 IA 20 9 MO 114 56 What statistical test should ...
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How, if ever, is quantile linear mixed model compatible with the signed rank test?

Paired Wilcoxon test evaluates median change rather than difference in medians. Quantile linear mixed model (defined for medians) evaluates change in the medians, rather than median change, as any ...
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Do box-plots fail to visualize Wilcoxon signed-rank tests?

Here someone recommended box-plots for visualization. But the following graph made me realize how box-plots can fail to meaningfully depict the Wilcoxon signed-rank test or sign tests in general: In ...
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Mean difference with paired pre- post- data, don't care about direction of change

I think I've confused myself into a corner. I have a pre- and post- measure, and the change is sometimes +ve and sometimes -ve. I want to see if there's a difference, regardless of sign change. What ...
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Testing mean in dependent non-normal samples

I have time-series data on the multi-level order book for one stock. I want to test whether the mean of the middle spread (bid-ask spread) is different from the mean of the spreads between the ...
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Proper statistical significance tests for small samples of unknown distribution

The title basically says it all; what is considered to be a proper statistical test in the literature for comparing small samples of unknown distribution? That is to say, I run an experiment something ...
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wilcox.test between multiple grouping variables in r [closed]

I have a data set with one numerical variable and 78 binary variables. I know how to perform multiple wilcox.tests between multiple numerical variables against one ...
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Ways to state relationships like “A explains x% the variation in B” but when variation is not present like for non-parametric tests

Example: Income explains 70% of the variance in expenditure. Variation in driving speed can be explained by drivers' age. How does one make such statements if the test used is a non-parametric one? I ...
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What's the appropriate test to be used in this study?

I was asked by an acquaintance of mine for support in interpreting a medical study. I don't work in healthcare, thus of course this was not professional advice. Two groups of people of size $n_1$ and ...
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R removing zeros for pseudomedian and its confidence interval in wilcox.test?

It makes sense to me that we need to remove zeros to calculate the p-value in a Wilcoxon signed rank test. What confuses me is that R seems to leave the zeros deleted when computing the pseudomedian ...
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Why p-values are different

I have a data of total number of mutations and fraction of mutations in each patient for three groups of patients I want to see if these three groups are different in terms of total number of ...
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Friedman's test with different # of answer choices

Greatly appreciate your help! I am analyzing paired data across 3 groups. Data within each group is ordinal (number of genes recommended for genetic testing, with each answer choice corresponding to ...
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Within subject, Multiple treatment: testing if each treatment further increases dependent variable?

Suppose I have data that looks something like the following for a single subject: Treatments: amount of a shot they receive, such as 5cc, 10cc, 15cc, 20cc Outcome of interest: energy level Question ...
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why wilcoxon signed rank test is better than binomial

Let $\vec{x}$ be 100 iid random varibles such that $x_i \sim \mathcal {N}(0,1)$ Let $\vec{y}$ be 100 iid random varibles such that $y_i \sim \mathcal {N}(1,1)$ For this example, the signed-rank test ...
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Early stopping in wilcoxon signed rank test?

I have decided to acquire N joint samples of variables X and Y (for example, N=200), and test whether their means are different using the signed-rank test. I will repeat this procedure many times, ...
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Perform signed rank test where there are duplicates in data?

How do you perform a rank test when there are duplicates in the data? that is, we have a dataset with numbers $1,1,1,1,3,3,3,3,4,4,4,4.$ and another dataset also with duplicates.... Is the sum of ...
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Wilcoxon signed-rank test on cross-validated values

Many neuroscience papers aim to estimate the significance of classification accuracy measures (AUC-ROC for example): can one classify such behaviors better than chance with such neuronal activities? ...
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In Wilcoxon signed ranked test, what box range represents? [duplicate]

I have used R programming language to perform Wilcoxon signed ranked test between two data: ...
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Can we use a Wilcoxon signed rank test on discrete, non-normal data in a small sample size?

I am looking to validate my decision to use a wilcoxon signed rank test to test for significance in my study. Essentially, I have a small sample size (n=10) and the data is paired. I am looking to ...
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Why do MATLAB and R give different results for Wilcoxon signed rank test?

I have tried to calculate Wilcoxon signed rank test p-values using MATLAB and R. Strangely, they give different results. Concretely, my code for MATLAB is ...
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How to conduct Holm's procedure for two-sided Wilcoxon signed rank test when conducting pairwise comparisons for multiple classifiers?

I am trying to compare the accuracies of m classifiers on multiple datasets. Following the suggestion of the JMLR'16 paper "Should We Really Use Post-Hoc Tests Based on Mean-Ranks?", I have decided to ...
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Is the r effect size that is used with Wilcoxon sing rank test also good to use with sign test

Is the r effect size that is used with Wilcoxon sing rank test (more about it here: https://www.researchgate.net/post/...
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Which test statistic to use for Wilcoxon signed rank test when n < 25

The z-statistic is based on an approximation of the normal distribution. When n samples are equal or greater than 25, it could be argued that a sample is asymptotically normal, and that a z-statistic ...

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