When to set priors or use default
I have recently run an experiment and shown an effect for group A on X. I would like to run the same experiment in group B to see if we get a different effect on X. Should I use default priors or set them according to the results of the first experiment?
Thanks
Comments
I think, if You compare group leave default or set the same priors in both.
You could analyse both A and B together, and see whether you find an interaction in an ANOVA. The approach you propose (i.e., the use the posterior from A as a prior for the analysis of
is appropriate if you want to test the hypothesis that B shows no effect whatsoever. But you indicated you want to know whether the effect in A is just as large as in B, and this calls for a test of an interaction.
Cheers,
E.J.