20k views

### How robust is ANOVA to violations of normality?

I have several dependant variables that are non normal in distribution: Kolmogorov-Smirnov test is significant, skewness ranges up to 8 for some variable, and kurtosis is generally about 2 but in a ...
• 121
9k views

### Normality test for repeated measures data

I've measured the motor function of the same subjects (n=6) over 7 different time points. I would like to know whether the mean motor function varies significantly with time (day 1 versus day 2 etc) ...
• 31
249 views

### Can you justify this very common (but seldom discussed) treatment of $p$-values?

This is a question about a seemingly illogical approach to hypothesis testing and p-value interpretation that I find almost universally endorsed. I’ll cite the answers at Can I trust ANOVA results ...
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216 views

### Normality within cells and non normality of residuals

In testing for the normality assumption for 2 way ANOVA, the question whether normality within cells implies normality of residuals has been asked before and I have found so far different answers from ...
4k views

### Should I use Kruskal-Wallis or Anova?

I'm trying to see if the weight of 9 different groups of people are the same using ANOVA. Then I have a dataset with almost 3000 observations and two variables basically Group: $1,2,\dots,9$ Weight: ...
3k views

### Two-way ANOVA when data is non-normally distributed

I'm trying to run a two-way ANOVA on a 375-sized dataset. I'm trying to navigate my way through the assumptions but need some assistance. Specifically, I have two groups as the IVs (1: Boys and Girls; ...
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1 vote
1k views

### Normal distribution assumptions in ANOVA vs. Linear Regression

I don't get it. I am planning to conduct a 2x2 between-subjects measurement with a sample size of 30 per cell, hence four groups that I want to test for the difference. Is there a difference in the ...
• 31
1 vote
1k views

### Methods for comparing two dissimilarity matrices

I have run cgMLST on E. coli isolates, then i ran the resulting allele labels through the "daisy" function in R with the "gower" setting to generate a dissimilarity matrix. I have subsets of isolates ...
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1 vote
801 views

### Two-way ANOVA with repeated measures and random effect and assumptions violated

I am trying to run a two-way ANOVA in JMP where I have the following variables- Fixed effects: 1. Genotype (categorical) 2. Temperature (categorical) Random effect: 1. Subject (animal) I am using ...
• 11
132 views

### Normal and non-normal distribution of data?

I am quite an amateur in statistics. I have data where I would like to test if I can perform parametric or non-parametric testing depending on if the data is normally distributed or not. The data has ...
32 views

### Evaluate significance for three different groups not normal distributed with different n

I have a group with three different treatments. One group gets shown 0 Tags, 4 and 7. N's are different in the range of 80-100 and data does not follow a normal distribution. I would also like to ...
• 103
125 views

### 2 factorial experiment (2 by 3). DV is NOT normally distributed

I just conducted an 2 factorial experiment that has 6 conditions (2 by 3). Specifically, my design is: IV1 = prior positive information (positive in A domain vs. control vs. positive in B domain) IV2 =...
601 views

### Non-normal distribution in anova - a big problem or not

Please don't close my question, it really is not a duplicate, no other answer on this forum is relevant to my case. Also, I have been advised that if I submit the spss output of my non-normally ...
530 views

### How to transform a set of negative values to obtain a normal distribution? [duplicate]

I am having quite a few problems with transforming a set of data with values between -1 and 0, as I need to normalise them. I tried to use the following formulae: [(𝑥−min(𝑥))/(max(𝑥)−min(𝑥))] AND ...