cd "C:\Users\sovid\OneDrive - The University of Kansas\Lectures\Soc910_AdvStat\examples"
use soc910_data_EASS2012.dta, clear

gen     yrsch = educyrs
replace yrsch = . if educyrs==88


* -----
* OLS
* -----
reg SWB heterophily R_age Female yrsch Employed SSS i.v2 [pw=weight]


* -----
* IPW
* -----

teffects ipw (SWB) (heterophily R_age Female yrsch Employed SSS i.v2, logit) [pw=weight]


* -----
* IPW: step-by-step
* -----

* Step 1: Estimate Logit
logit heterophily R_age Female yrsch Employed SSS i.v2 [pw=weight]

* Step 2: Estimate the predicted prob
predict P

* Step 3: Compute IPW values
gen     IPW=1/P     if heterophily==1
replace IPW=1/(1-P) if heterophily==0

gen     newIPW = weight * IPW

* Step 4: Estimate OLS with new weight
reg SWB heterophily [pw=newwt]



* -----
* testing balance between heterophily = 1 and heterophily = 0
* -----

tab v2, gen(ctry)

tabstat R_age Female yrsch Employed SSS ctry1-ctry4 [aw=weight], by(heterophily)
tabstat R_age Female yrsch Employed SSS ctry1-ctry4 [aw=newIPW], by(heterophily)

reg R_age heterophily [pw=weight]
reg R_age heterophily [pw=newIPW]

reg SSS heterophily [pw=weight]
reg SSS heterophily [pw=newIPW]

foreach i of var R_age Female yrsch Employed SSS ctry1-ctry4 {
	reg `i' heterophily [pw=newIPW]
	}