Hi Iam new to SAS and statistics,
Can I know which is the best approach to transform non normal data(positive,negative,zero values) distribution to NORMAL.
I came across few internet sites which mentioned to perform Log transformation by adding a constant.But some says this is not a good approach.
I have attached(T test file) on which I want to run "T test " on "overall difference variable " to see if my template worked better - here post test score is the score after template where as pretest score is the scorer before giving template(i.e instructions).
Since the data is skewed and I ran some normality test check "Shapiro wilk" and I got a P value which is less than 0.05.
So based on the shapiro result and my histogram on "overall score difference " variable I came to know my variable is not normally distributed so I cant run T test and decided to do a normal transformation.But my difference variable has negative,positive,zero values.
Thanks for your help in advance.Please ask me questions if I am not clear as this is my first post.