I have already used the logit transform on my outcome variables (which are displayed in percentages). However, this obviously gives me -INF values and since my data includes a lot of zeros in some instances, this makes it hard to analyse.
I have now tried an empirical logit transform, adding the smallest non-zero promotion to the numerator and denominator of my variables to remove the -INF values (as suggested in http://www.esajournals.org/doi/abs/10.1890/10-0340.1).
However, now my data are very non-normal again. I have tried experimenting with error terms to add to the logit transform but since have had no luck.
Is there any way I can find a value to add to my transformation to ensure normality?