<hansl>
set echo off
set messages off

open rac3d.gdt --quiet
list X = SEX INCOME ILLNESS ACTDAYS HSCORE

# Poisson regression
poisson DVISITS 0 X

# Initial OLS to get starting values for the coefficients
series fake_y = ln(DVISITS+1)
ols fake_y 0 X --quiet
list xList = $xlist
matrix b = $coeff
matrix mX = {xList}

mle loglik = DVISITS*Xb - m
    series Xb = mX * b
    series m  = exp(Xb)
    series e  = DVISITS - m
    deriv b = {e} .* mX
end mle --hessian

# Poisson regression with Offset
lAge = ln(AGE)
poisson DVISITS 0 X ; AGE

series fake_y = ln(DVISITS+1) - lAge

mle loglik = DVISITS*Xb - m
    series Xb = mX * b
    series m  = exp(Xb) * AGE
    series e  = DVISITS - m
    deriv b = {e} .* mX
end mle --hessian
</hansl>