program define dmtest, rclass
*! v1.3 gmh july 11 2002
syntax varname [if] [in], m1(string) m2(string)
tempvar pm1 pm2 v1 v2 lhs1 lhs2 dif factor1 factor2 touse

mark `touse' `if' `in'
markout `touse' `m1' `m2'


qui probit `varlist' `m1' if `touse'
qui predict `pm1'
qui predict `v1' , stdp

qui probit `varlist' `m2' if `touse'
qui predict `pm2'
qui predict `v2', stdp



qui gen `lhs1' = `varlist' - `pm1'
qui gen `lhs2' = `varlist'- `pm2'

qui gen `factor1' = normd(invnorm(`pm1'))
qui gen `factor2' = normd(invnorm(`pm2'))
capture drop R1* R2*
capture gen one=1
qui foreach var in  `m1' one {
	gen R1_`var' = `factor1'*`var'
	}
qui foreach var in  `m2' one {
	gen R2_`var'= `factor2'*`var'
	}

qui gen `dif' = `pm1'-`pm2'


di _n in gr " Davidson-MacKinnon Nonnested Model Test for Binary Regression Model" 
di " "


qui count if `touse'
global N  = r(N)

di in gr " Number of Observations = " in ye $N
di " "

** test model 1
 qui reg `lhs2' `dif' R2_* [w=1/ `v2'] if `touse', nocon
di in gr "TEST OF 1 VERSUS 2 (R says Model 1 adds pred. power)"
test `dif'=0

return   scalar df_r1= r(df_r)
return   scalar F_1=r(F)
return   scalar df_1 = r(df) 
return   scalar p_1 = r(p) 


** test model 2 
 qui reg `lhs1' `dif' R1_* [w=1/ `v1'] if `touse', nocon
di in gr "TEST OF 2 VERSUS 1 (R says Model 2 adds pred. power)"
test `dif'=0

return   scalar df_r2= r(df_r)
return  scalar F_2=r(F)
return   scalar df_2 = r(df) 
return  scalar p_2 = r(p) 
return scalar N = $N

end