use "http://www.learneconometrics.com/class/stata/rwm2003.dta", clear
summarize

gen H =  hospvis >0
gen D =  docvis>0
tabulate H D
global xlist female age income hhkids educ married
biprobit (H = $xlist) (D = $xlist)
biprobit (H = $xlist) (D = $xlist), vce(cluster id) coeflegend
margins, dydx(married) predict(equation(H))
margins, dydx(married) predict(equation(D))
margins, dydx(income) predict(equation(D))

use "http://www.learneconometrics.com/class/stata/burnett.dta", clear
summarize
global x1list acrep econfac pctwecn relig
global x2list acrep relig pctwfac nor sou mid 
biprobit (gndrecon=$x1list womstud) (womstud=$x2list)