All Questions
Tagged with nonparametric normality-assumption
52
questions
1
vote
1
answer
241
views
Which statistical test should I use if the assumptions of a 2-way ANOVA are not met?
My study design consists of two factors (one with 2 levels, the other with 6) and a continuous response variable. In order to analyze the influence of both factors on the explanatory variable I built ...
0
votes
1
answer
429
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Testing for normality of difference between pre-post scores
I'm currently trying to decide what test to run on SPSS for my data. I am comparing the effects of 3 different interventions on trauma scores. I have both pre and post-scores.I have created a ...
7
votes
2
answers
1k
views
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-...
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 $\mu, \sigma^2$ ...
3
votes
1
answer
695
views
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 ...
0
votes
0
answers
31
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Anova violates normality assumption for error data
I have a 2 x 2 repeated measures ANOVA (N = 51) with Error Rate data as the dependent measure. The error data violates the normality assumption, even when outliers are removed. I have looked at the ...
0
votes
0
answers
67
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Comparing non-normal data between three groups
I am analyzing a dataset, where I have 3 categories (independent variable), and one continuous value (dependent variable). I am studying if the continuous value is significantly different between the ...
2
votes
2
answers
115
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Distribution and variable analysis
I am doing a statistical test (program used is SPSS). On the basis of distribution and sample size, I have to chose the correct variable analysis. I also have to justify every decision. I have two ...
0
votes
1
answer
57
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Importance of normality testing in clinical trials / AB tests
I’m curious to read about the importance of normality testing in AB tests and clinical trials.
It seems that there is a lot of mixed (and strong) opinions about the necessity for normality testing, ...
2
votes
1
answer
70
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Alternatives to ANOVA to find differences between three groups?
So my data is looking at the incidence of emotions within therapy sessions. I am looking at three groups that I suspect have different pattern across several emotions
Group 1 n=36
Group 2 n=12
Group 3 ...
1
vote
0
answers
15
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Looking for associations between nominal and non-parametric continuous data
I'm a first-year BSc Biology student working on my end-of-module stats project, so that's the expected level of my work.
I need to find associations between hindlimb length and frog locomotor modes (e....
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 = ...
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 ...
2
votes
1
answer
5k
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Paired t-test of a non-normal data with sample size 66
I have a paired data with n=66. I understand that normality condition of differences data should be met to conduct a paired t-test. However, from the histogram, it doesn't appear so normal. The p-...
0
votes
0
answers
275
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How can I perform a Tetrachoric and Polychoric Correlation on variables that aren't normally distributed?
From everything I have read, both tetrachoric and polychoric correlations assume normal distributions. However, the data I want to conduct these correlations with is not normally distributed. Does ...