How to model Interaction term in Regression equation estimation using stan

[torkar]

Have you tried to change this,

@volabos

Y ~ normal(beta0 + beta1 * X1 + beta2 * X2 + beta3 * X1 : X2, sigma);

to this,

Y ~ normal(beta0 + beta1 * X1 + beta2 * X2 + beta3 * X1 * X2, sigma);