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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Analysis of repeat measure ordinal patient data across 3 time points (ordinal regression vs. Wilcoxin rank sum)?

I am conducting a study of a number of patients with a disease, and using an ordinal scale assessment of functional status at 3 different time points. In this example we can say that I have 100 ...
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Does Paired T-Test provide the same result as Wilcoxon Signed Rank Test on the same dataset?

In principle they are trying to test the differences in dependent data. However, do they always provide the same outcome on the same dataset? What happens if we get contradictory result by using both ...
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Should I perform multiple testing correction (FDR) for all the P-values regardless if they derive from Ttest or Wilcoxon?

There are 100 participants and I want to test if 50 metabolites change before and after intervention (antiobesity drug). First, I check the normality for each variable, and then I perform a T-test or ...
73 views

Which statistical method can be used to compare the values of the same variables measured from different views?

I got a biological data set, where I need to run a statistical analysis on. The data was created on a mass spectrometer and contains the intensity values for around one hundred lipids. The analysis ...
28 views

How to handle the zero deviation with Wilcoxon test and t-test(with zero standard deviation data)

I am a newbie of statistics I am looking for a statistical test for zero standard deviation data VS a distributed data Here is the example: ...
62 views

Variance of Wilcoxon Signed-Rank Statistic

Problem Statement: Let $T$ denote the Wilcoxon signed-rank test for $n$ pairs of observations. Show that $E(T)=(1/4)n(n+1)$ and $V(T)=(1/24)[n(n+1)(2n+1)]$ when the two populations are identical. Note:...
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Is 90% of the use of paired signed-rank Wilcoxon test incorrect due to violated distributional assumption of symmetry, or is it more general?

Everywhere, including forums - also this one, handbooks of statistical tests discussions, I can read that the paired Wilcoxon test does require the assumption of symmetry. This would mean, that: Most ...
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Significance testing the difference in dimensionality between conditions

I would like to test the hypothesis that under two experimental conditions there is a difference in data dimensionality. Measures of dimensionality are complicated statistics of the data; for example, ...
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Wilcoxon signed-rank test can be a test for comparing means but not for comparing medians?

Wikipedia says that we can rewrite the hypotheses of the one-sample Wilcoxon signed-rank test in terms of expected value (as "a test for the location of the mean") if the following ...
38 views

how handle zeros and ties in one-sample Wilcoxon signed rank test

I have the results of a Likert question about Covid's impact on students' lives regarding university. 189 answered this question and the answers are as the following: 20 people answered "-2"...
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Which items in two ranked lists are ranked significantly different?

I have 91 items ranked by different demographic groups of questionnaire participants. The rank lists for each group are all the same length and contain identical items. I understand that I can perform ...
32 views

Is it reasonable to compare models by confidence interval width?

I am estimating values for the number of users holding a stock. Afterwards, I subtract the number of users that actually hold the stock in the time period from it. Let's call the result of the ...
406 views

Statistically Comparing the Similarity Between Lists (e.g Food Preferences)

I have the following question: Are there any statistical methods (e.g. hypothesis tests) that allow you to compare the order of two different lists? Suppose there are two students : John and Sarah. ...
136 views

Statistical significance test of kurtosis differences

I would like to raise a problem that bothers me. However, I would like to point out right away that my question is purely theoretical, and the data presented here comes only from a computer experiment ...
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Analyzing the results of Likert scale with one sample Wilcoxon signed-rank test

I have the results of a questionary with 2 subjects and each of them includes 4 sub-questions in the form of Likert items. The questions are about the impact of a situation on people's lives and the ...
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Wilcoxon Sign-Rank Test with before/after treatment and control groups

Here is the setup of my experiment. I have 500 storefronts that are all part of the same chain brand. I've selected 250 of them to test an advertising intervention, and want to know whether the ...
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Can I use one sample wilcoxon signed rank test for time series data where I need to check if all of the data points are below a theoretical value?

I have time-series data and I want to check if the data I collected is below a certain theoretical value. Is the one-sample Wilcoxon signed-rank test the best way for my objective? Some background ...
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Pairwise comparison - too many groups

I have 23 groups that I am comparing. I was just going to show the distribution of the groups with boxplots but a reviewer of my manuscript wants me to do group testing. The trouble is that pairwise ...
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Mean difference analysis for a paired data with zero inflation. Can Wilcoxon test work?

I have a set of data that represent the sum of white matter streamlines termination in 64 regions of interest in the brain surface collected from 40 subjects. Below is an example of a paired data of ...
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If I use the wilcox.test from R for paired data, what exactly it returns? I want to compute the effect size based on that

I want to calculate effect size for the paired Wilcoxon (signed rank). There are two options: Z/sqrt(N_pairs) or the rank-biserial correlation. The wilcox.test(... paired=TRUE) returns "V". ...
63 views

How to detect differences between two repeated measures for not-normally distributed variables, adjusting for a continuous covariate?

I'll explain briefly the experimental set-up. One gruop of subject measured in two conditions: A: with treatment (Instrumented gait analysis with foot orthosis) B: without treatment (Barefoot ...
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Questions about derivation of Wilcoxon Signed Rank Test

I am learning some statistics on my own after my bachelor's degree. I am trying to understand the properties of the test statistics for the Wilcoxon Signed Rank Test (for paired data). ...
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Codes for Wilcoxon matched paired test with scatter plot [duplicate]

How can I modify the following codes in order to get a Wilcoxon matched paired test with scatter plot? ...
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Analysing before and after results of likert scale

I am a student with little knowledge on statistics. I ran a between subject experiment with 2 conditions, the control and test condition. In both situations I asked participants a set of 8 questions ...
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Wilcoxon test or paired T test for matched data

I am working on comparisons between two time points 2013 and 2019, I have 180 subjects. I have a numeric "score" from 2013 and 2019. I calculated the average score at both time points and ...
24 views

When the ties are the majority in Wilcoxon

I´m doing a comparation in a sample with an n=300. I did the wilcoxon rank test to compare if there were difference in the individuals in two situations. The problem is that the ties are allways huge, ...
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How to compare the distribution of partially paired ordinal data

I have multiple methods that are intended to measure the same ordinal quantity about a number of entities. For each of these methods, some of the values are missing and I know that this missingness is ...
285 views

Paired t-test with multiple observations per pair

I have a bunch of websites websiteA....websiteZ for example. Now I have an optimization technique that possibly improves the performance of these websites. I want to check whether this technique ...
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Assessing Consistency and Agreement of Two Groups of Raters in an ordinal dataset

I'm using a real dataset of convenience to look at one group of subjects who are being assessed for "frailty". The goal is to see whether assessments by non-experts are comparable to experts....
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I'm looking for a statistical test more robust than the sign test for my experimental analysis

I made an exploratory experiment that consists of a pair of readings. I used Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) to read elements on several mineral surfaces, getting ...
35 views

Understanding the statistical scenario using R with basic concepts

I am new to statistics, trying to solve below problem, Two companies selling toothpastes with the lable of 100 grams per tube on the package. We randomly bought eight toothpastes from each company A ...
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Wilcoxon Test with n=4 per group not significant, why?

I have the price per bottle Preis Normal of a certain drink, the difference is the number in each packaging. the Magnum is double the size of the normal bottle, so <...
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Is the wilcoxon signed-rank test suitable for zero-inflated data?

I have data that look like this: (There's 285 entries) These are paired data, in that each line represents a single seal group that has been counted for entanglements using two different methods of ...
66 views

Understanding a proof of the relation between Walsh averages and Wilcoxon signed rank test statistic

I am trying to understand a particular proof of the relation between Walsh averages and the Wilcoxon signed rank test statistic, as given in the book Statistical Inference Based on Ranks by T.P. ...
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Can someone explain to me need symmetrical distribution for Wilcoxon signed rank test?

So I am confused. I understand that Wilcoxon signed rank test does not need to have normal distribution (hence why it is used when your data is non-normally distributed in place of paired samples t-...
69 views

Statistical significance test for 5-fold cross validation on a single dataset

I have used stratified 5-fold cross validation to generate five data folds to compare several (N) deep learning models on a single dataset. Now, I have the fold-wise test accuracies for all of the ...
225 views

Paired wilcoxon vs linear mixed effects model with random intercept - the 2 interpretations

I would like to know what would be the key differentiator assessing change over time between a wilcoxon paired test and a linear mixed effect model with random intercept. I did my analysis in R: The ...
163 views

Calculating statistical power for non-parametric data (using Wilcoxon signed-rank tests)

I am performing a prospective-design analysis of Patient Reported Outcome Measures from a registry of patients. I have used Shapiro-Wilk test throughout to test for normality. All data is paired and ...
35 views

What is the drawback of using a non-parametric test when parametric alternative could have been used? [duplicate]

I want to analyze the difference between two paired samples. My initial plan was to compare them using the Wilcoxon test because I didn't want to bother checking whether the data is properly ...
56 views

Friedman and wilcoxon signed rank test: how to interpret?

For our thesis we're comparing EMG activity with no insoles, with insoles just received and with insoles after 8 weeks wearing them. In SPSS we did following actions: Friedman test to see if there is ...
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Paired Hypothesis Testing with Conversion Samples

Let's assume I have 100s of websites on which I am tracking conversion. At some point I change something to all websites. I want to measure if there is a statistical significant difference between my ...
395 views

ties in Wilcoxon t test in R

I have a paired data with a small sample size of 19 subjects who gave different scores at time 1 ($T_1$) and time 2 ($T_2$). I'd like to conduct a Wilcoxon test using R, because my data are not normal....
514 views

How best to present paired Wilcoxon test [duplicate]

I created a survey to find out if people spent more time in their gardens in 2020 when compared to 2019. I did a paired sample Wilcoxon test to compare the two and found a significant difference but ...
77 views

Wilcoxon signed-rank test for count-proportions?

Let's say that I have several agents able to take action A or B, and I am interested in showing that taking action A is more likely. So I have a table that looks something like A B 10 2 14 6 ... .....
63 views

Which one to use: Cliff's Delta or Vargha-Delaney's A12 to know the effect size?

I have to compare the predictions of two regression models (both are predicting on same dataset, but one is using entire data and another one is using only pruned data). To know whether there mean ...
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Does Wilcoxon Signed Rank (paired test) in R automatically analyse data by row?

I have multiple rows of observation periods [OP] (of varying durations) showing the average food intake rate of the first quarter of the OP compared to the last quarter of the OP. See the table below....
52 views

Compare gain scores of two groups of unequal size and not normal distribution

I am trying to determine the effectiveness of a learning intervention that we developed. We had two groups, a control and experimental group, where we applied the intervention to the experimental ...
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Wilcoxon signed rank test for heavily tied data

I am having trouble conducting Wilcoxon test analyses on heavily tied data. I have outlined my problem as best I can below, how I have tried to address it, and the questions I have. I'd be really ...