[amelia] 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

> working space problem. > > Now another challenge confronts us. > > During stage 1 of 4, (EM), the program bombs after iteration 34, and

> 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

> for the correct variablres. The program was using the conditional

> variables are fully obserfed, and 1 is nominal. The 12 category

> 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

> > > > > > I'm a political scientist from Michigan State University who, with > Robert Mattes of the University of Cape Town, co-directs the

> The Afrobarometer is a large-scale, cross-national survey research

> 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

> missing data, both randomly distributed and country specific. On the

> in the AMELIA manual, we have cut down on missingness by rescaling

> knows". We have also reduced the core variables for analysis to 37

> trying to implement AMELIA. > > > > > > Our basic problem is that AMELIA will not run when we include all

> cases. It keeps giving us an error message that says "insufficient > workspace memory". We can get AMELIA to generate 5 imputed data sets

> 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

> 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

> RAM and 20 Gbyte disk. > > > > > > Our questions are as follows: > > > > > > * Is there a limit to the number of cases that AMELIA can handle?

> it work on a data set of 37 variables by 21,000 cases? > > > > > > * Does the error message refer to AMELIA's workspace or the

> 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

> 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

> country, when included). > > > > > > We will make one more effort to call you today before Cape Town

> down for Easter. In case you want to call, you can reach us at 011 27

> 234 0333. I have copied this message to your associates at Harvard in

> you aren't in this week. If we have not spoken today, would you be so

> 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