I would like to sample my model from a point prior. At the moment I have my hand-crafted R code for this, but I thought why not to use brms to do that.
I figured, that I could simply use the “Fixed_Param” thing from Stan. So I would setup my model in brms once, setup the design and then only sample a set of parameters for which I would call brm to then actually sample the data according to the design and the model.
… but brm does not let me choose the “Fixed_Param” thing from Stan - it’s not allowed. Why not? To me this looks very useful - or is there another way of doing what I have outlined?
I know that there is the constant prior in more recent brms versions… but for one, I am cannot easily bump the version nor would I like to recompile the model just for that.
Suggestions? Maybe there is a way via make_stancode… but if so, how would I turn things again into a brms object where I get the nice post processing?