data{ int n; vector[n] x; } transformed data{ real alpha; //hyperparameter of center real beta1; //hyperparameter of variance real beta2; //hyperparameter of variance alpha <- 100; beta1 <- 5; beta2 <- 5; } parameters{ real mu; //parameter of center real vari; //parameter of variance } model{ mu ~ normal(0,alpha); vari ~ inv_gamma(beta1, beta2); x ~ normal(mu, sqrt(vari)); } generated quantities{ real sigma; //stardard deviation sigma <- sqrt(vari); }