* compute average over time by firm
* use collapse commands
collapse (median) sale (median) xsga , by(gvkey)
gen ln_s = ln(sale)
gen ln_xs = ln(xsga)
xtile k=ln_s, nq(10)
mat mat_results = [.,.]
forvalues j=1/10{
reg ln_xs ln_s if k == `j'
mat mat_results = mat_results \[ ( _b[ln_s], _se[ln_s])]
}
matlist mat_results
svmat mat_results
keep if mat_results1 ~=.
gen index = (_n)*10
* Elasticity of SGAX with respect to sales
graph twoway (scatter mat_results1 index),xtitle('Percentile %') ytitle('Elasticity')xlabel (0 (10) 100)
怎么在图中加入95%confidence interval? 如果用gen UB=_b[ln_s] + 1.96*_se[ln_s]
gen LW =_b[ln_s] - 1.96*_se[ln_s]这应该加到哪呢?
谢谢


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