I have two subgroups of structure (bone structure) and I want to test if there is any difference of size (area) between them, and if there is, how important this difference is. The first set is a group non-heated, and the second was heated. I wanted to do a Bayesian T-test (Mann-Whitney because my data isn't normal and the variance of the two groups isn't equal).
I am just not sure about the prior distribution to set for the test. I understand what is a prior distribution but I am not sure if I have any ... My take is that if I had some information about my priors, I think it would be more clear than that and I would know. Is it better to keep the default prior in JASP (cauchy = 0,707) if I am not sure about the priors distribution (I've seen this in some publications)? Is it often that we can't add some priors knowledge to those tests?