misterabc
11-09-2008, 12:04 PM
I am trying to analyze the effects of a particular type of course students can take (3 levels: haven't taken the course, taken one course, taken 2 courses) on college gpa. I'm using hs gpa and SAT scores as covariates. My problem is that my response variable gpa is not distributed normally (which isn't too surprising since 4.0 is our upper bound cutoff).
I thought that the usual regression/ANOVA techniques are no longer valid in this situation. I've tried some transformations (log, sqrt, arcsin(sqrt), inverse) that have all failed to produce normal data. Does anyone have any suggestions about how I can proceed (specific transformations or another method entirely)? Do I even have to be concerned with this problem?
I thought that the usual regression/ANOVA techniques are no longer valid in this situation. I've tried some transformations (log, sqrt, arcsin(sqrt), inverse) that have all failed to produce normal data. Does anyone have any suggestions about how I can proceed (specific transformations or another method entirely)? Do I even have to be concerned with this problem?