Dear All,

I am new to stata and I am using Heckpoisson, a poison regression model with endogenous sample selection model to estimate factors influencing access to extension services and intensity of of access. I have the model result already but I have no clue of how to estimate the marginal effect (dydx) after Heckpoisson. I need you suggestion or help.

Below is the model output:

Poisson regression with endogenous selection Number of obs = 293
(25 quadrature point s) Selected = 141
Nonselected = 152
Wald chi2(9) = 39.34
Log pseudolikelihood = -397.3723 Prob > chi2 = 0.0000
------------------------------------------------------------------------------------------
| Robust
ext_freq | Coef. Std. Err. z P>|z| [95% Conf. Interval]
-------------------------+----------------------------------------------------------------
ext_freq |
age_hhh | -.0040843 .0034685 -1.18 0.239 -.0108824 .0027139
gender_hhh | -.2542102 .0785204 -2.82 0.005 -.3754374 -.067643
hh_size | -.0046676 .0156446 -0.30 0.765 -.0353305 .0259953
dist_mkt | .0075753 .013998 0.54 0.590 -.0198998 .0349712
own_cash_crop | .1196532 .0692318 1.73 0.084 -.0160386 .2553451
input_acces0 | .2543907 .0800315 3.05 0.002 .0870918 .4008095
aware_extension_services | -.2671813 .0863115 -3.15 0.002 -.4409838 -.1026488
access_2crdt | .07612 .0672013 1.14 0.253 -.0549509 .2084733
farm_size1 | .0021675 .0178802 0.15 0.881 -.032373 .0377159
_cons | 1.263667 .2010278 6.15 0.000 .8426601 1.630675
-------------------------+----------------------------------------------------------------
access_to_extension |
hh_size | -.051465 .031816 -1.62 0.106 -.1138233 .0108933
dist_mkt | -.0452002 .0317816 -1.42 0.155 -.107491 .0170905
own_cash_crop | -.0665395 .161095 -0.41 0.680 -.3822798 .2492008
input_acces0 | -.0579019 .1757906 -0.33 0.742 -.4024451 .2866414
aware_extension_services | .6452373 .1814888 3.56 0.000 .2895259 1.000949
access_2crdt | .3881123 .1606434 2.42 0.016 .0732571 .7029675
sell_rice | .3996281 .2191917 1.82 0.068 -.0299798 .8292361
farm_incom_hh | .0000456 .0000128 3.56 0.000 .0000205 .0000707
crop_dive | -.3390377 .3519390 -1.06 0.288 -.9650316 .2869562
main_inc_source | -.0995744 .1876322 -0.53 0.596 -.4673268 .268178
_cons | -.1595383 .4452855 -0.35 0.730 -1.026583 .7189037
-------------------------+----------------------------------------------------------------
/athrho | 1.515521 .248586 6.54 0.000 1.137901 2.11234
/lnsigma | -3.783098 .9520586 -4.03 0.000 -5.703099 -1.971098
-------------------------+----------------------------------------------------------------
rho | .9636253 .0322574 .8137061 .9711619
sigma | .0261155 .0222056 .0033356 .1393039
------------------------------------------------------------------------------------------
Wald test of indep. eqns. (rho = 0): chi2(1) = 33.01 Prob > chi2 = 0.0053

My regards,

T. Sumo