*! version 1.0.0  12/20/94                              STB-24: sg32
program define vif
	version 4.0
	if "$S_E_cmd" != "fit" {
		error 301
	}
	local varlist	"$S_E_vl"
	local if	"$S_E_if"
	local in	"$S_E_in"
	local wgt	"$S_E_wgt"
	local exp	"$S_E_exp"


	local wtexp = ""
	if "`wgt'" != "" & "`exp'" != "" {
		local wtexp = "[`wgt'`exp']"
	}

	parse "`varlist'", parse(" ")
	mac shift
	local varlist = "`*'"

	local nvif : word count `varlist'

	tempname ehold vif mvif
	scalar `mvif' = 0.0
	quietly {
		noi di
		noi di in gr "Variable |      VIF      1/VIF  "
		noi di in gr "---------+----------------------"
		local i 1
		estimate hold `ehold'
		capture {
			while `i' <= `nvif' {
				local dep : word `i' of `varlist'
				local len = length("`dep'")
				local idx = index("`varlist'","`dep'")
				local idm = `idx'-1
				local idk = `index'+`idx'+`len'+1
				local ind = substr("`varlist'",1,`idm')
				local ind = "`ind'" + /*
				*/	substr("`varlist'",`idk',.)
				fit `dep' `ind' `if' `in' `wtexp'
				scalar `vif' = 1/(1-_result(7))
				scalar `mvif' = `mvif'+`vif'
				local skip = 9-`len'
				noi di in gr _col(`skip') "`dep'" _col(10) /*
				*/ "| " in ye %9.2f `vif' /*
				*/ "    " in ye %8.6f 1/`vif'
				local i = `i'+1
				if _rc {
					estimate unhold `ehold'
					error _rc
				}
			}
			noi di in gr "---------+----------------------"
			noi di in gr "Mean VIF | " /*
			*/ in ye %9.2f `mvif'/`nvif'
		}
		estimate unhold `ehold'
		error _rc
	}
end