I was wondering whether anyone would be help with a problem Im having with
building Double Hurdle models in stata. I have the following code from a
recently published article but stata says that d is an �ambiguous
abbreviation�. If I change the name of the variable d to dd throughout the
program, then I get a different error message � variable dd not found.
I was wondering whether there was an obvious mistake that is immediately
noticable in my work (included below), or whether there is some precode that
I need before the program will function correctly.
rename loss_only y
capture program drop dh
program define dh
version 6
args lnf theta1 theta2 theta3 theta4
tempvar d p z p0 p1 l yt
quietly gen double `d'=$ML_y1>0
quietly gen double `p'=normprob(`theta3')
quietly gen double `l'=`theta4'
quietly gen double `yt'=($ML_y1^`l'-1)/`l'
quietly gen double `z'=(`yt'-`theta1')/(`theta2')
quietly gen double `p0'=1-(`p'*normprob(-`z'))
quietly gen double `p1'=(($ML_y1+(1-`d'))^(`l'-1))*`p'*normd(`z')/`theta2'
quietly replace `lnf'=ln((1-`d')*`p0'+`d'*`p1')
end
ml model lf dh (y = curr_bal) () (d= gbp) ()
ml search
ml maximize
I have just included curr_bal and gbp as two example independents I plan on
using to predict loss_only (y).
