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Re: st: stcox: negative HR when used in bootstrap


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: stcox: negative HR when used in bootstrap
Date   Tue, 7 Aug 2007 20:02:45 +0100 (BST)

bootstrap, reps(100): boot_hr

should be 

bootstrap drug=r(drug), reps(100): boot_hr

Hope this helps,
Maarten

--- Michael McCulloch <mm@pinest.org> wrote:

> 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
> *
> *   For searches and help try:
> *   http://www.stata.com/support/faqs/res/findit.html
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
> 


-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


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