Thanks for the clear instructions. I will try this. Just to be sure, if I am interested in modeling odds ratios for sick, I should code the sick samples =1? Also, when I use the Contrast command, it seems that I can only choose the first or last as a reference category in the Indicator contrast. If for example, I need to set the reference category to the 3rd group, does this mean I would have to recode everything with the reference group=1 ? Thanks for your help again, I am fairly new to Statistics in general.

Thanks, I will edit my original text to include some output and commands!. Just to be clearer, my independent variable is categorical (7 distinct groups). I would like to use 1 of the group as a reference category.

Thanks for your input, I am trying to determine the % variation from one SNP in the supplementary data but it looks like I can't from whatever information provide.

Thank you for your comment, I will look at your links more thoroughly.