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RE: st: bootstrap fails with qreg


From   "Feiveson, Alan H. (JSC-SK311)" <alan.h.feiveson@nasa.gov>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: bootstrap fails with qreg
Date   Wed, 3 Sep 2008 14:35:23 -0500

 Jeff - Thanks for the explanation and fix. Also, thanks for your quick
response. 

Al

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Jeff
Pitblado, StataCorp LP
Sent: Wednesday, September 03, 2008 1:36 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: bootstrap fails with qreg

Alan Feiveson <alan.h.feiveson@nasa.gov> is trying to use the
-bootstrap- prefix command with -qreg-:

> Hi - I tried to get bootstrapped standard errors with median 
> regression by using the -bs- command. The regression appears to run 
> through all the iterations, but at the end ,there seems to be a 
> problem in collecting all the estimates to get the bootstrapped 
> standard error. I notice that Bill Gould has provided code in STB-9 
> (sg11_1.ado) to do this, but this is from some years ago and the 
> -qreg- version that it uses might not be the one we now have with 
> Stata 10.1. So my questions are
> 1) Is sg11-1.ado still the best way to do this ,other than 
> bootstrapping by hand with -bsample-?
> 2) Is there a workaround using the current Stata 10.1 cabilities? 
> 3) Can this be done with cluster sampling? 
> 4) I'm curious - what is the reason for the failure (see below)?
> 
> 
> AL Feiveson
> 
> . bs: qreg z4 zrs0
> (running qreg on estimation sample)
> 
> Bootstrap replications (50)
> ----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
> ..................................................    50
> 
> Median regression                                    Number of obs =
> 1860
>   Raw sum of deviations 1217.215 (about -.99425226)
>   Min sum of deviations 1217.215                     Pseudo R2     =
> 0.0000
> 
> last estimates not found
> r(301);

The -bsqreg- estimation command fits quantile regression with bootstrap
standard errors; however, it does not support cluster sampling.

The -qreg- estimation command does not support the -bootstrap- prefix.
This is mostly due to programming details and allocation of development
resources.



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