Best regards, Taghreed
-----Original Message-----
From: Gary King [mailto:king@harvard.edu]
Sent: Tuesday, 19 March 2002 19:21
To: adamt
Cc: evansd; James Honaker; Kenneth Scheve
Subject: Re: problem with Amelia
why don't you first see whether Amelia (through DataLoad) loaded the data
in properly. Load it in and look at the descriptive statistics to make
sure. If that doesn't work, try the new version of Amelia which has a
new
Dataload incorporated. If that doesn't do
it, you can save the data in
ascii, and load it into Amelia that way, which we know always works.
It sounds like that is the issue, but let me know if not. I'm CCing my
coauthors in case they have other ideas.
Gary
: 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 Tue, 19 Mar 2002 adamt(a)who.ch wrote:
>
> > Dear Dr King,
> >
> > My name is Taghreed Adam and I am working in WHO in Chris Murray's
> > cluster. Chris asked me to use Amelia to replace the missing values
in
the
> > dataset that I am working with. This is prior to running a
regression
to
> > predict unit costs per bed day in
hospitals. The dataset I am using
for
> > Amelia includes 21 variables; the log
of the unit cost per bed day (
$),
a
> > set of explanatory variables such as log of GDP per capita,
occupancy
> > rate (%), Average length of stay (days)
etc. There are also
variables
> > that describe the nature of the unit
cost data - e.g. whether
capital
>
costs, drugs, and other incidental costs are included (all dummies).
Then
> > there are desciptors like the country code,the region code, whether
it
is
> a public or private hospital (dummy) etc...
The total number of
hospitals
> > for which we have observations is 1097. The maximum percentage of
> > missingness of observations per variable is 53%, i.e., the least
number
of
> observations I have for any variable is
around 600. they are all
numeric
> variables.
>
> What I first did is to make sure that all variables included in the
model
> are normally distributed. The the data is
saved in excel version 2,
with
> > no headings.
> > In Amelia, I set _AMempri option to 1 to control for the high degree
of
>
missingness of some of the variables, I identified fully observed
> variables using the _AMfully and the one nominal variable for which
there
> > is missing data using the _AMnoms. (The other nominal variables do
not
> > have missing data)
> >
> > What happens when I run Amelia is either that it crashes just after
I
>
specify the input file name or it gives me the following message:
elements
> > of m can not be zero. I tried to check whether I have any variable
that
is
> > coded as a string variable that might explain this message but it is
not
> > the case. I have no observations or
variables that are all zeros or
> > missing. I do not think it is a memory problem as my computer has
550
MHz
> > memory and I do not work with other software while it is running.
> >
> > I tried to delete some of the variables, e.g., some of the dummies
or
> > those that might be highly correlated
with other variables and I
tried
to
> > run it again with a total of 8 variables. I used stata this time as
the
> > type of input file. It started running
about 7 hours ago and is
still
> > running but clearly something is wrong
as the number of iterations
is
now
> > 115000.
> >
> > I would be grateful if you could give me some advice on what could
be
the
> > source of the problem and what else I can try to do. I would be
happy
to
> > call you if it will make it easier to
discuss. We have discussed
this
> > > question extensively with Josh Salomon who has also run out of ideas
>about
> > > what we can try next.
> > >
> > > I am looking forward to hearing from you.
> > > Yours sincerely,
> > > Taghreed
> > >
> > >
> > > Dr Taghreed Adam
> > > Global Programme on Evidence for Health Policy (GPE) and;
> > > Child and Adolescent Health Department ( CAH)
> > >
> > > World Health Organization
> > >
> > > 20 Avenue Appia
> > >
> > > CH-1211 Geneva 27
> > >
> > > Switzerland
> > >
> > > Tel: +41 22 791 3487
> > > Fax: +41 22 791 4328
> > > office: 3164
> > > e-mail: adamt(a)who.int
> > >
> > >
> >