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st: solving equations with stata


From   Gianfranco Spiteri <Gianfranco.Spiteri@hpa.org.uk>
To   statalist@hsphsun2.harvard.edu
Subject   st: solving equations with stata
Date   Wed, 4 Jan 2006 16:34:42 -0000

Hi,
I am trying to perform a downweighting process for a dataset I am working on
(for an outbreak detection system of infectious diseases based on the
Farrington method). As part of the process I have got to a point were I have
a list of residuals (res). I need to create weights for the original data
based on these residuals using the following formulas:
weight = a * res ^ -2
where a is a constant such that:
sum of all weights = n

where n is the number of observations (n is 35 or less with this method)
I'm sure there is a relatively straight forward way of doing this in stata,
but I cant seem to find it. Can anyone help me out,
thanks
Gianfranco

-------------------------------------------------------------

Gianfranco Spiteri
CDSC (NI)
McBrien Building
Belfast City Hospital
Lisburn Road
Belfast
BT9 7AB

Gianfranco.Spiteri@hpa.org.uk
Tele: +44 (0) 28 90263765   Fax: +44 (0)  028 90263511 


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