All Questions
Tagged with nonparametric normality-assumption
52
questions
2
votes
2
answers
370
views
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 $\mu, \sigma^2$ ...
- 235
3
votes
1
answer
692
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 ...
- 53
0
votes
0
answers
30
views
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 ...
- 113
0
votes
0
answers
66
views
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 ...
- 21
2
votes
2
answers
114
views
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 ...
- 21
0
votes
1
answer
57
views
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, ...
- 67
0
votes
1
answer
412
views
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 ...
- 1
2
votes
1
answer
68
views
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 ...
- 21
1
vote
0
answers
15
views
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....
- 11
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 ...
- 441
3
votes
3
answers
146
views
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
0
votes
0
answers
272
views
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 ...
- 101
3
votes
2
answers
967
views
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
0
votes
0
answers
175
views
Is there a non-parametric test to replace repeated-measures ANOVA in R?
I have a data set with 41 individuals, male and female, and 3 different measurements of a variable for each individual. The data is not normally distributed, nor does it have equal variances between ...
6
votes
2
answers
8k
views
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