nb1
. clear
. set obs 50000
. gen x1= runiform()
. gen x2= runiform()
. gen xb = .5 + 1.25*x1 -- 1.5*x2
. gen exb=exp(xb)
. gen idelta = 2*exb
. gen xg=rgamma(idelta, 1/idelta)
. gen xbg = exb*xg
. gen nb1y = rpoisson(xbg)
NB2
clear
set obs 50000
set seed 4321
gen x1 = rnormal()
gen x2 = rnormal()
gen xb = 2 + 0.75*x1 - 1.25*x2
gen a = .5
gen ia = 1/a
gen exb = exp(xb)
gen xg = rgamma(ia, a)
gen xbg = exb * xg
gen nby = rpoisson(xbg)
glm nby x1 x2, nolog fam(nb ml)
我用NB1模拟产生数据，如何再用NB2去拟合NB1产生的数据啊？上面程序是用NB1和NB2分别产生数据，然后拟合，我如何用一个模型去拟合另一个模型？
还有谁会NB-P模型模拟数据的编程？求帮忙