Linked Questions

9
votes
3answers
1k views

Assessing the power of a normality test (in R)

I want to assess the accuracy of normality tests over different sample sizes in R (I realize that normality tests may be misleading). For example, to look at the Shapiro-Wilk test, I'm conducting the ...
8
votes
4answers
1k views

Is it realistic for all variables to be highly significant in a multiple regression model?

I want to regress the fuel economy on engine displacement, fuel type, 2 vs. 4 wheel drive, horsepower, manual vs. automatic transmission, and the number of speeds. My data set (link) contains ...
4
votes
2answers
11k views

How to get the expected counts when computing a chi-squared test?

I just have 1500 data points in excel. However, I want to do a chi squared test to prove if the data is normaly distributed. My question is: How to calculate the expected range for such a large data ...
9
votes
3answers
3k views

Equivalence tests for non-normal data?

I have some data that I can't necessarily assume to be drawn from normal distributions, and I would like to conduct tests of equivalence between groups. For normal data, there are techniques like TOST ...
2
votes
4answers
3k views

Justifying normal approximation of experimental data

Background: In connection with the question here I came upon a more interesting question. I believe the question is large and distinct enough to have it's own thread. Of course I might be mistaken, ...
9
votes
2answers
3k views

Goodness of fit to Poisson Distribution

What are some of the well known statistical tests to measure goodness of fit of observed random variables to a poisson distribution? I know the Kolmogorov-Smirnov test is one such, are there any ...
4
votes
3answers
8k views

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 ...
4
votes
3answers
5k views

Methods to check if my data fits a distribution function?

My shortened data is: y <- c (2,2,1,5,6,7,1,2,1,6,6,7,3,2,4,4,4,4,3,3,9,1,1,9) I firstly normalize my data: ...
5
votes
1answer
3k views

Can one measure the degree of empirical data being Gaussian?

I would like to inquire about a simple test I might be able to perform to determine how 'nicely Gaussian' my empirical data are. If they are 'nicely Gaussian', then I can perform some other analysis, ...
10
votes
1answer
6k views

I log transformed my dependent variable, can I use GLM normal distribution with LOG link function?

I have a question concerning Generalized Linear Models (GLM).My dependent variable (DV) is continuous and not normal. So I log transformed it (still not normal but improved it). I want to relate the ...
9
votes
2answers
7k views

Kolmogorov–Smirnov test: p-value and ks-test statistic decrease as sample size increases

Why do p-values and ks-test statistics decrease with increasing sample size? Take this Python code as an example: ...
6
votes
1answer
1k views

Can Median Absolute Deviation (MAD)/SD be used to determine if a distribution is normal or not?

I have recently come across this post on Median Absolute Deviation (MAD). The Wikipedia article here, by the article as an estimator Standard deviation of the distribution is 'k' times MAD, where the ...
3
votes
3answers
10k views

Repeated measures ANOVA or Friedman test?

I have a study with 35 subjects who received hypercoagulability testing at 4 different times (before surgery, after, at 1 week, and at 1 month). Each subject has 9 different test of hyper ...
1
vote
2answers
13k views

What to do when Kolmogorov-Smirnov test is significant for residuals of parametric test but skewness and kurtosis look normal?

I have conducted a parametric test in a study, n=290. I want to assess whether the residuals of this test are normally distributed. The skewness and kurtosis of the residuals are -0.017 and -0.438 ...
2
votes
2answers
12k views

Comparing z-scores from different data sets

Is it possible to use z-score as a number to compare two different data sets (none of them with normal distribution) and identify which one has an average z-score higher than another? Thanks!

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