Linked Questions
369 questions linked to/from Is normality testing 'essentially useless'?
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Normality test and Outlier detection [duplicate]
In this question, I would like to ask two things:
outlier detection
normality test
Details are as follows:
I need to detect and remove outliers in my data. Before doing that, I want to test if my ...
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Fitting data to a log-normal distribution [duplicate]
For a simulation study I've been trying to find an appropriate distribution for job handling times in R. I have a very large dataset of 77010 records (handling time in seconds).
I've been exploring ...
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Is the practice of doing normality test before doing t test wrong? [duplicate]
When I read research papers, I saw that many people do a normality test first, then decide if a t-test or a non-parametric test should be applied.
I have a concern about such practice. Let’s say the ...
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What is exactly the non-normality requisite for nonparametric tests? [duplicate]
As the title says, what is exactly what is being tested before deciding to use a non-parametric alternative test (as Kruskal-Wallis for ANOVA, or Mann-Whitney's U for student's t)?
Most sources are ...
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Why according to distribution graph it's normally distributed, but Jarque-Bera test shows non-normally distributed? [duplicate]
I am working on Kaggle's house pricing exercise and I cannot understand something. I watch and read articles on normality tests, and more specifically JB test, but I cannot understand why according to ...
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Testing for normality with small sample sizes in order to use t-test [duplicate]
I run into a conundrum when determining whether a small sample is appropriate for a t-test. I know that if I meet the assumptions, a t-test produces approximately correct inference with any sample ...
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Is it possible to test for a Gaussian distribution? [duplicate]
Suppose that I have $n$ independent samples from a probability distribution. I believe that the distribution is Gaussian ($G$) but I don't know; then my question is: does there exist a test such that ...
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Normality test with p-value equal to zero [duplicate]
I have an array dataset of about 650.000 points. I want to test if the dataset follow a normal distribution or any other distribution. The first thing I did was to split the data in groups, find the ...
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How to assess plausibility of mixed model and goodness of fit [duplicate]
I am trying to understand which would be the most reasonable fitting form my data. Despite there are more appropriate appproach to test such relationship, the aproach I was suggested was to use the ...
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Is it always encouraged to do a normality test before choosing parametric and non-parametric tests? [duplicate]
For a given dataset, if a normality test introduces type I or type II errors, how reliable are the subsequent results based on parametric or non-parametric techniques? What should we do to minimize ...
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If the data is not normally distributed and the skewness is = 0.208 SE of skewness is 0.144 , is it acceptable to use t-test? [duplicate]
The sample size is 288 and by Shapiro- Wilk test the data is not normally distributed.
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Linear regression: fit seems good, but residuals not normal. How to fix [duplicate]
I am using the famous diamonds dataset and I'm using linear regression to fit the following model:
$\ln(\text{price}) = \beta_0 + \beta_1 \cdot \ln{\text{x}} + \beta_2 \cdot \text{clarity}$
where ...
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Normality Assumption - Help! [duplicate]
I am relatively new to statistics and struggle with the normality assumption (where and how it needs to be assessed).
I understand that parametric tests need the data to be normally distributed. The ...
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normality testing [duplicate]
Good day,
I am a medical student currently working on a thesis focused on metabolic syndrome. My sample size is 45 individuals. I have encountered multiple challenges in assessing the normality of my ...
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Distribution looks roughly normal on a q-q plot, but has a p-value of 0.0 for the Shapiro-Wilk normality test. How to interpret? [duplicate]
The distribution is as follows:
However the Shapiro-Wilk test yields a p-value of 0.0 and a W statistic of 0.9. There are over 7,000 values in the sample.
Note, the quantile values have been ...
