Questions tagged [shapiro-wilk-test]

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What is the difference between Shapiro-Francia and Shapiro-Wilk tests of normality?

I apologize for this easy/basic question. Please forgive me if this is a duplicate question. I've been researching the Shapiro-Wilk test (1965) of normality for a project. In doing so, I found an ...
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Why is the Shapiro-Wilk $W$ statistic defined the way it is?

In the original paper (section 2.2.), we can see that derivation of the $W$ statistic goes along these lines: Let let $m_i$ be the expected value of the $i$-th order statistic of a random sample of $...
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Confused about testing my data for normality

I am starting some quantitative analysis of a dataset. My sample size is just over 100 (approx 110) and before doing the descriptive stats I attempted some normality testing to determine if I should ...
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Intraclass correlation with skewed dataset

There is data on 20 people taking the same test 5 times each to look at the repeatability of the test. I understand that intraclass correlation is usually the best test to use to look at a question ...
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Does the effect size of a normality test determine whether the normality assumption can be ignored for parametric tests with large samples?

Reading this question and this question and the answers and comments, I have another question. Does the effect size of a normality test determine whether the normality assumption can be ignored for ...
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Shapiro–Wilk normality test

I'm trying to check for normality using Shapiro–Wilk normality test. I have a two-way ANOVA (2x3) and would like to run this test on each of the 6 groups. Which function should I use to be able to run ...
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Three different dep. variables are significant on the Shapiro-Wilk test. That's not good. Is there anything I can do to show normality assumption?

My DVs (Facefactor, Legfactor, UpperBodyFactor) are showing sig. results on Shapiro-Wilk, meaning they are not normally distributed. The histograms look rather normal however. Is there any way to show ...
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42 views

Different result from shapiro test for seemingly similar residual distributions of gls models

I have a question regarding the distribution of residuals in a gls model. I built a gls model with a numerical dependent variable (Y), a Factor A (categorical, 2 levels) and a Factor B (categorical, 3 ...
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p-value for Shapiro-Wilk is high but data doesn't appear normal

I'm a beginner at stats and I'm trying to understand p-values for paired t-test and Shapiro-Wilks using the JASP Moon and Aggression data set (hope the screenshot resolution is ok - click on the image ...
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1answer
33 views

Reasoning for tranforming linear model to log-level

I have a multiple linear regression model and found that my error terms are not normally distributed. When looking at the histogram of the dependent variable, it looks like below. I am not sure how ...
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32 views

My normality plot and Shapiro's test say different things

I have an LMER, and I want to check for normality; my plots show this: However, my shapiro test shows this: ...
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275 views

Performing a shapiro-wilk test on residuals from an LMER and repeated-measures ANOVA

I would like to perform a Shapiro-Wilk test on my data which takes the form of an LMER. The LMER model is named lmerabsolute. ...