I have data that looks like this:
control = [0,0,1,0,1,1,0,1...] treatment-1= [1,0,0,0,1,1,0,1...] treatment-2= [1,1,1,1,1,1,0,1...]
The experiment was whether or not a certain return policy (control = no fee, t1 = 5 dollar fee, t2 = 8 dollar fee) would effect whether or not a person bought an item. Each person was exposed to only one treatment group. There are 300,000 samples for each treatment group.
What is the best way to test for significance of treatment? My first inclination was to run ttest's between pairs of 2 treatments, but my p-values were 0, which made me suspicious. Further research indicated this may be a proportions problem and maybe a chi square test is preferred, but I do not really understand why.
Please advice on how to test if there are significant differences in outcomes based on treatment. Thanks.