Dear Altruist,
1. I could implement the following commands with success. (STATA-14.2)


probit smk price_per_pack $x_list_reg
margins, eyex(price_per_pack) atmeans


However, the following does not work

ivprobit smk $x_list_reg (price_per_pack=tax_rate)
margins, eyex(total_income) atmeans // does not work


Error: r(459);could not calculate numerical derivatives -- discontinuous region with missing values encountered.

Any idea??



2. I also tried

probit smk price_per_pack $x_list_reg
margins, expression(normalden(xb())*_b[price_per_pack]*68.60907/normal(xb())) // worked

but again,

ivprobit smk $x_list_reg (price_per_pack=tax_rate)
margins, expression(normalden(xb())*_b[price_per_pack]*/normal(xb())) // did not work

Would love to have some feedback on this as well.

Cheers