Hello everyone,

I am trying to compute tariff equivalent effects following the approach suggested in An Advanced Guide to Trade Policy Analysis. page 30 of the book. I attach below the code proposed in the book and the error I get when I try the second line of the code:

Code:
*** Model for GVC participation
asdoc ppmlhdfe gvc_total regulatory_distance contig applied_tariff ln_dist comlang_off comlang_ethno comcol comrelig col45 comleg_pretrans sibling rta if exp!=imp, a(exp_time imp_time) vce(cluster pair_id) replace

* Tariff equivalent effects
scalar TariffEquivalentRD_1 = (exp(_b[regulatory_distance]/(-_b[applied_tariff])) – 1) * 100

unknown function ()
r(133);

Does someone know how to fix this issue?

Thanks in advance