st: combining two Kaplan Meier graphs, with only one legend

[Michael McCulloch <mm@pinest.org>]

Hello,
I'm seeking advice on how to combine two Kaplan Meier graphs, with 
only one legend. Using the hip2.dta dataset, I've created one KM 
graph where calcium is <10, and one where calcium is >10. I'd 
appreciate any suggestions on how to show:

(a) on each sub-graph:
	the sub-titles
		"Calcium<10"
		"Calcium>=10"
	the x-label "Survival time in months"

(b) on the combined graph only:
	the legend " ___ Protected"  and  "---- Not protected"
	a main title "Benefit of Protection Based on Calcium Level"


****** begin example *******
use hip2.dta, clear

* KM compare protect = yes to protect = no, where Calcium<10
sts graph if calcium<10, by(protect) title("Calcium<10", box 
bfcolor(white)) ///
	saving("cal<10", replace ) legend(label(1 "Protected") 
label(2 "Not Protected")) ///
	lpattern(l - dot _) lcolor(black black black black) 
xtitle("Survival time in months") l2title("Percent surviving") 
xmtick(0(10)40)

* KM compare protect = yes to protect = no, where Calcium>=10
sts graph if calcium>=10, by(protect) title("Calcium>=10", box 
bfcolor(white)) ///
	saving("cal>=10", replace )	legend(label(1 "Protected") 
label(2 "Not Protected")) ///
	lpattern(l - dot _) lcolor(black black black black) 
xtitle("Survival time in months") l2title("Percent surviving") 
xmtick(0(10)40)

* FIGURE 1: KM, all stages by stage, combined into one graph
graph combine cal<10.gph cal>=10.gph, saving("all_cal", replace ) 
rows(2) cols(2) iscale(0.5)
****** end example *******
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