Posts Tagged “normality”

Normal Distribution

You (Probably) Don’t Need to Test Your Data for Normality

Anyone who analyzes data knows (or should know!) the importance of not violating the assumptions of the tests one runs. And for common tests like t-tests, correlation, ANOVA, and regression, one of the assumptions is that the variables are normally distributed. One method that some people use, then, is a test for normality of the data, such as the Kolmogorov-Smirnov (K-S) test or the Shapiro-Wilk (S-W) test. If the test indicates a deviation from normality, they might try a transformation, or use a more robust statistical test to analyze their data. I’m here to say that this is going to make life hard for yourself. Here’s the summary of this article right up front: If you want to see if normality assumptions are violated, don’t use a normality test.Continue Reading