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Re: st: What is this problem called?

From   Michael Foster <>
Subject   Re: st: What is this problem called?
Date   Sat, 17 Nov 2007 11:28:16 -0500

Hi Kiernan,

The key issue is what constitutes "stabilizes"--to me, that sounds like a time series problem. I'm not a time series expert (really, I'm a time series ignoramus). What I would do, though, is look in a time-series book to find a way to determine a test for stability then look at how adding time points affects this test.
Presumably from the first to the second surgery and so on, you could reject stability. Then by the kth, you no longer could do so-

something like that--michael

Kieran McCaul wrote:


A colleague has asked me the following question:

Suppose a surgeon performs a number of surgical procedures using a new
technique. He/she records the operating time for each operation. How
would the data be analysed so as to determine the number of procedures
performed before the operating time stabilises?

I haven't come across a problem quite like this before, but it seems to
me that it's a question that might arise, for example, when evaluating
the implementation of new industrial or manufacturing processes.

I have an idea about how I would approach this analysis, but first I'd
like to have a look at what others may have done.

Searching the literature is difficult though if you don't know what the
problem is called.

Does anyone recognise this problem or something analogous to it and can
you give me a name I can search on or point me to a few relevant papers.
I can back-track though the literature from there.

Thanks in advance,


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

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