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Re: st: problem in ICE for multiple imputation


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: problem in ICE for multiple imputation
Date   Thu, 12 Jul 2007 07:00:19 +0100 (BST)

--- tang5@purdue.edu wrote:
> A survey dataset has four variables q098 q099_2, q100 and 130 with a
> heavy amount of missing values for each of them. 
> I ran the ice command and get the following message: 
> 
> "I detected a problem with running uvis with command mlogit on
> response q098 and covariates q099_2 q100 q130.
> 
> The offending command resembled:
> uvis mlogit q098 q099_2 q100 q130 ,   
> 
> With mlogit, try combining categories of q098, or if appropriate, use
> ologit
> 
> unrecognized command
> r(199);"
> 
> Then I use the option cmd(q098:ologit) since that variable could be
> an ordinal variable. I got the following message:
> "I detected a problem with running uvis with command ologit on
> response q098 and covariates q099_2 q100 q130.
> 
> The offending command resembled:
> uvis ologit q098 q099_2 q100 q130 ,   
> 
> unrecognized command"

Try combining some of the categories, like I virtualy always do when I
use rep78 in my examples:
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html#recode .

-mlogit- and -ologit- somtimes won't converge if one of categories is
very small. More seriously, the algorithm underlying -ice- (a Gibbs
sampler) won't converge if another variable or variables have all
missings for one value of q098. This is serious as -ice- will not and
cannot automatically check for convergance. I got the impression that
Patrick now checks for these problems and issues this warning message.

Hope this helps,
Maarten

-----------------------------------------
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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