st: stcox: negative HR when used in bootstrap

[Michael McCulloch <mm@pinest.org>]

Hello,
I'm puzzling over why the same stcox argument would return a negative 
HR value when bootstrapped. Any comments or critique would be 
welcomed!

*--------------- begin code in question -----------------------

sysuse cancer, clear
stset studytim, failure(died)
stcox drug

sysuse cancer, clear
stset studytim, failure(died)
capture program drop boot_hr
	program define boot_hr, rclass

	* cox
	stcox drug
	indeplist, local
	foreach var of varlist `X' {
		return scalar `var' = exp(_b[`var'])
	}

end
set seed 12358
bootstrap, reps(100): boot_hr
*--------------- end code in question -----------------------

--

Michael McCulloch
Pine Street Foundation
124 Pine St., San Anselmo, CA 94960-2674
Tel:	(415) 407-1357
Fax:	(415) 485-1065
mcculloch@pinestreetfoundation.org
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