Hi, I am trying to estimate the following model with a standard deviation that is random. The model to be estimated is : Zt=a*Z(t-1) + b*Y(t-1)+c*D(t-1)+ exp(sigma(t)*epsilon. where Zt is a policy shock (deviation from mean). Y is deviation from mean of log of output. D is change in debt/output ratio. epsilon is N(0,1). Please note the Sigma is time variant. How should I estimate this using STATA 15? I was trying to use bayes/bayesmh but with no success. Appreciate any advice as to how to proceed