*Regression results
use DID.dta,clear

xtreg Score Did i.year,fe r
outreg2 using 1.doc,replace tstat bdec(3) tdec(2)

xtreg Score Did Te Asset Lev Tps Fa Ttc TobinQ i.year,fe r
outreg2 using 1.doc,append tstat bdec(3) tdec(2) 

psmatch2 Treat Te Asset Lev Tps Fa Ttc TobinQ,outcome(Score) logit ties ate common radius caliper(0.05) neighbor(2)
xtreg Score Did Te Asset Lev Tps Fa Ttc TobinQ i.year if _weight!=.,fe r
outreg2 using 1.doc,append tstat bdec(3) tdec(2) 



*Parallel trends
gen policy=year-2015 
tab policy
replace policy = -4 if policy < -4


forvalues i=4(-1)1{
	gen pre`i'=(policy==-`i')
}

gen current= (policy==0)

forvalues i=1(1)6{
	gen post`i'=(policy==`i')
}


xtreg Score pre4 pre3 pre2 o.pre1 current post* Te Asset Lev Tps Fa Ttc TobinQ i.year,fe 
est store m1  
*picture
#delimit ;
coefplot m1, keep(pre* current post*)
    aseq swapnames noeqlabels vertical omitted
    ciopt(recast(rarea) color(gs14))
    msize(*0.5) c(l) color(gs0) 
    xlabel(1 "-4" 2 "-3" 3 "-2" 4 "-1" 5 "0" 6 "1" 7 "2" 8 "3" 9 "4" 10 "5" 11 "6", labsize(*0.85)) 
    ylabel(-0.2(0.05)0.2, angle(0) format(%4.1f) labsize(*0.85) grid) 
    xline(4, lp(dash)) 
    yline(0, lp(dash)) 
    legend(off)
    graphregion(fcolor(gs16) lcolor(gs16)) 
    plotregion(lcolor("white") lwidth(*0.9));
#delimit cr


*placebo-controlled study
permute Did beta=_b[Did] se=_se[Did] df=e(df_r),reps(1000) seed(1001001) saving("simulations.dta",replace): xtreg Score Did Te Asset Lev Tps Fa Ttc TobinQ i.year,fe r



*picture
gen t_value=beta/se
gen p_value=2*ttail(df,abs(beta/se))
twoway (scatter p_value beta, msymbol(smcircle_hollow) mcolor(blue)), ///
title("安慰剂检验") ///
xlabel(-0.3(0.1)0.3, format(%4.1f)) ylabel(0(0.2)1,angle(0.1) format(%4.1f)) ///
xline(-0.242, lwidth(vthin) lp(shortdash)) xtitle(系数) ///
yline(0.1,lwidth(vthin) lp(dash)) ytitle(p值) ///
legend(label(1 "kdensity of estimates") label( 2 "p value")) ///
plotregion(style(none)) ///
graphregion(color(white)) //