I'm testing the Dirichlet distribution with pyStan 3.7. I'm getting a warning that alpha has two prior, I don't get why.
data {
int<lower=1> T;
int<lower=1> K;
int y[T, K];
}
parameters {
simplex[K] theta[T];
real alpha;
}
model {
alpha ~ cauchy(0, 1);
for (t in 2:T) {
theta[t] ~ dirichlet(alpha + theta[t-1]);
}
}