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RE: st: What is this problem called?

From   "Kieran McCaul" <>
To   <>
Subject   RE: st: What is this problem called?
Date   Fri, 16 Nov 2007 17:14:46 +0900

Thanks, Maarten

Kieran McCaul MPH PhD
WA Centre for Health & Ageing (M573)
University of Western Australia
Level 6, Ainslie House
48 Murray St
Perth 6000

-----Original Message-----
[] On Behalf Of Maarten buis
Sent: Friday, 16 November 2007 4:37 PM
Subject: RE: st: What is this problem called?

--- Kieran McCaul <> wrote:
> For example, if 200 procedures were performed,
> there might be little difference in the average time for the first 50
> procedure compared to the last 50 procedures.  I suspect, though,
> that there might be a large difference in the variance of these
> It's the change in variance as more procedures are performed that's
> interested. 

This seems to be a hetroscedastic model, have a look at chapter 10 of
(McCullagh & Nelder 1989). A similar model that deals with discrete or
ordinal data is sometimes called a hetregeneous choice models, this is
discussed here:

P. McCullagh, John A. Nelder (1989), "Generalized Linear Models",
Second Edition, Chapman & Hall/CRC. 

Hope this helps,

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

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