Thanks.
Once I have identified country as fully observed (AMfully), should I NOT
then declare it as nominal (AMnoms)? Does that tell Amelia to attempt to
impute it?
----- Original Message -----
From: Gary King <king(a)harvard.edu>
To: bob <bob(a)idasact.org.za>
Cc: Bob at UCT <rmattes(a)cssr.uct.ac.za>za>; Amelia Listserv
<amelia(a)latte.harvard.edu>
Sent: Tuesday, April 30, 2002 3:37 PM
Subject: Re: Amelia Query
It might be that you have identified a fully
observed variable as
something to be imputed (you could try it without it), but I'm not
positive. I'm forwarding this to the new Amelia listerv. Maybe one of my
colleagues or someone else can help?
Gary
On Tue, 30 Apr 2002, bob wrote:
> Gary,
>
> Thanks for your earlier reply re: Amelia. I think we have cleared up
the
> working space problem.
>
> Now another challenge confronts us.
>
> During stage 1 of 4, (EM), the program bombs after iteration 34, and
gives
> the message, "sweep: elements of m
cannot be zero. Exec stopped in line
> 79."
>
> I have run this twice to make sure I had checked the correct global
commands
> for the correct variablres. The program was
using the conditional
model. 2
> variables are fully obserfed, and 1 is
nominal. The 12 category
"Country"
> variable is both fully observed and
nominal.
>
> Does the error message have something to do with this?
>
> Presently, there are 37 variables, and just over 20,000 observations.
>
> This is not time series data, but should both Country, as well as
> Rural/Urban be identified as cross sections?
>
> Any help you can give would be greatly appreciated.
>
> Regards,
>
> Bob Mattes
>
>
> ----- Original Message -----
> From: Gary King <king(a)harvard.edu>
> To: mike <mike(a)idasact.org.za>
> Cc: <ajoseph(a)fas.harvard.edu>du>; <tercer(a)latte.harvard.edu>du>;
> <kscheve(a)latte.harvard.edu>du>; Robert Mattes <bob(a)idasact.org.za>
> Sent: Thursday, March 28, 2002 3:05 PM
> Subject: Re: your mail
>
>
> >
> > have a look at this:
http://gking.harvard.edu/amelia/node55.html
> > I think it will answer your question.
> > Gary King
> >
> > : Gary King, King(a)Harvard.Edu
http://GKing.Harvard.Edu :
> > : Center for Basic Research Direct (617) 495-2027 :
> > : in the Social Sciences Assistant (617) 495-9271 :
> > : 34 Kirkland Street, Rm. 2 HU-MIT DC (617) 495-4734 :
> > : Harvard U, Cambridge, MA 02138 eFax (928) 832-7022 :
> >
> > On Thu, 28 Mar 2002, mike wrote:
> >
> > > Dear Gary King,
> > >
> > > This follows up on the message I left on your voice-mail earlier
today.
> > >
> > > I'm a political scientist from Michigan State University who, with
> Robert Mattes of the University of Cape Town, co-directs the
Afrobarometer.
> The Afrobarometer is a large-scale,
cross-national survey research
project
> on public attitudes to democracy and markets
in 12 African countries.
> > >
> > > We are currently analyzing a fairly large data set (150 variables x
> 21,000 cases) from Round 1 of the Afrobarometer. It contains quite a
bit of
> missing data, both randomly distributed and
country specific. On the
advice
> in the AMELIA manual, we have cut down on
missingness by rescaling
"don't
> knows". We have also reduced the core
variables for analysis to 37
before
> trying to implement AMELIA.
> > >
> > > Our basic problem is that AMELIA will not run when we include all
21,000
> cases. It keeps giving us an error message
that says "insufficient
> workspace memory". We can get AMELIA to generate 5 imputed data sets
for a
> sub-sample of 2000 cases. It takes about
half an hour. And we can get
> AMELIA to complete the iterations in Step 1 on 5,000 cases. But the
program
> bombs in Step 2 when it tries to impute
covariances (after about 45
> minutes), again yielding the same error message. Attempts at 10,000 and
> 21,000 will not even start running.
> > >
> > > We have here a Pentium 4 computer with 1 Ghtz hard drive and 256 mg
free
> RAM and 20 Gbyte disk.
> > >
> > > Our questions are as follows:
> > >
> > > * Is there a limit to the number of cases that AMELIA can handle?
Will
> it work on a data set of 37 variables by
21,000 cases?
> > >
> > > * Does the error message refer to AMELIA's workspace or the
computer's
> workspace? In other words, does the problem
lie in the capacity of the
> hardware or the software?
> > >
> > > * If we include a 12-value multinomial variable for "country",
does
> this take us over AMELIA's limit of 40 variables? We have tried to run
the
> program both with and without this variable,
with the same problematic
> result.
> > >
> > > * For your information, we have specified one nominal variable
> (country, when included) and two fully observed variables (one of which
is
> country, when included).
> > >
> > > We will make one more effort to call you today before Cape Town
closes
> down for Easter. In case you want to call,
you can reach us at 011 27
83
> 234 0333. I have copied this message to
your associates at Harvard in
case
> you aren't in this week. If we have
not spoken today, would you be so
kind
> as to reply by e-mail, with a copy to
bob(a)idasact.org.za.
> > >
> > > With many thanks for your time. We look forward to using your
valuable
program.
>
> Yours,
>
> Mike Bratton.
>
>
>
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