Specifying prior parameter as input in data section?

Is there any difference between specifying priors manually in code (model 1) or as input in the data section (model 2)?
I am asking because model 1 allows me to change the prior when running the stan code while model 2 means I have to change the priors in the stan code and save them manually. Any idea if there is a difference and if there is, what is going on?

Model 1:
data {
int <lower=0> AG;
int <lower=0> rep_mean;
}
model {
reporting_rate0 ~ normal(rep_mean, 1);
}

Model 2:
data {
int <lower=0> AG;
int <lower=0> rep_mean;
}
model {
reporting_rate0 ~ normal(-2, 1);
}

Hi @sk8. I think you already answered your question?
It’s not clear if your question is really about Stan or not, what goes on behind the scenes might differ between Stan and PyMC.

Hi @drbenvincent, indeed my questions is about Stan, I’ll post it on the right forum. Thanks!

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