How do I put multiple qreg function lines and the x and ys on the same graph?

[Jiale Zhang]

For example, I have a set of data x and y.
I now regress y=a+bx for 20th, 30th, 40th percentile of y.
After that I hope to get a graph with the 3 regression lines and all the original x and ys.
What should the codes be for that?

[FernandoRios]

Hi Jilae
For a simple example like the one you describe, the following may help:

 use http://fmwww.bc.edu/RePEc/bocode/o/oaxaca.dta, clear
 
foreach i in 10 25 50 75 90 { 
qreg lnwage c.age##c.age##c.age, q(`i')
predict ln_wage_`i'
label var  ln_wage_`i' "Ln wages q`i'Hat"
}

two scatter lnwage age, msize(tiny) || line ln_wage_* age, sort

HTH