All Questions
Tagged with nonparametric normality-assumption
52
questions
7
votes
2
answers
1k
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Is the inference from a parametric test valid when the population distribution is not normal?
This question arose from reading this post: T-test for non normal when N>50?
In the response to this post, the author outlines really well that the assumption of normality with regard to the t-...
- 71
7
votes
2
answers
12k
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Non-Parametric altervative to one sample t-test
I have a the following hypothesis: $H_0: \mu=4$, $H_1: \mu\neq 4$, which I wanted to test using a one sample t-test.
However, my data is not normally distributed and a transformation was not found. ...
- 486
6
votes
2
answers
3k
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Wilcoxon Test - non normality, non equal variances, sample size not the same
I know there are already a lot of posts out there, but I couldn't find this exact combination in any of them.
Comparing two samples (Prices associated with men and with women), but I have neither the ...
- 71
6
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2
answers
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Can we ALWAYS assume normal distribution if n >30?
I'm in a debate with a coworker and I'm starting to wonder if I'm wrong but the internet is confusing me more.
We have continuous data $[0, \infty)$ that is retrospectively selected on individuals. ...
- 185
6
votes
2
answers
370
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What is an example of data where the permutation test succeeds but a normal t-test fails?
In literature, I normally see authors use a two sample permutation test on normal data to show that it works as well as the two sample t-test. However, the real power for permutation tests should be ...
- 2,107
4
votes
3
answers
13k
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Normality assumption and sample size
I know this is a very debated topic, even on this site, but I still couldn't find an answer to my problem.
Recently I am working with large samples (300, 400 and more). For now, I am trying to use ...
- 115
3
votes
1
answer
695
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I have applied many statistical tests to my data, but still cannot determine normality
I have run multiple tests to determine normality on my dataset, but I am unsure which one to adhere to, especially since my histograms, density plots, and QQ plots leave much to be desired in terms of ...
- 53
3
votes
2
answers
2k
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Theil-Sen estimator assumptions
I found by accident the nonparametric Theil-Sen Estimator as a replacement for standard OLS linear Regression. How well does it perform with autocorrelated data, non-normal residuals and ...
- 69
3
votes
1
answer
943
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Wald-Wolfowitz Runs Test for Normality Assumptions Testing
Some guys told me that it's appropriate to use Wald-Wolfowitz Runs Test as a normality test (like Shapiro-Wilk's or Kolmogorov-Smirnov...). Do you think this is good way to test normality assumptions?
- 2,211
3
votes
3
answers
149
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Problem with a single outlier, non-normal data, and unequal sample distributions
I am wanting to compare two independent groups on a likert-like item. To explain, the dependent variable is structured so that a 1 = <1 units, 2 = 1-<2, 3 = 2-<3, all the way up to option 7 = ...
- 31
3
votes
3
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Tests of normality - qq and Shapiro-Wilk
I am new to the world of stats ...
My data had a log normal distribution, so transformed by log to get it nearer normal distribution. This is real-world data.
From here I want to establish if my data ...
3
votes
2
answers
975
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Does aligned rank transform ANOVA require normally distributed data?
Initially, I wanted to do a two-factorial (4x3) repeated measures ANOVA in order to analyse my data.
To be more precise, I do have two factors with factor1 having 4 levels (A, B, C, D), factor2 having ...
- 31
3
votes
1
answer
5k
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Two-Way Non-Parametric Test for Non-normal Data?
I have an unbalanced design with two factors, gender and site. I'm trying to test for differences in a size variable. Levene's test reveals that the data has equal variances. However, log transformed ...
- 45
3
votes
0
answers
76
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Comparison of cell counts with a right censoring
I have cell counts related to the action of different microorganisms and I want to compare their distribution. It's supposed they follow a normal distribution after a log transformation, but I can't ...
- 75
2
votes
2
answers
370
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How could Lilliefors use Monte Carlo if the estimand is not distribution-free?
Lilliefors test is a well-known statistical test for normality. Its idea is based on the Kolmogorov-Smirnov test, except the CDF is replaced by the CDF of the normal distribution with $\mu, \sigma^2$ ...
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