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Re: st: global curve fitting


From   Joseph Coveney <jcoveney@bigplanet.com>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   Re: st: global curve fitting
Date   Thu, 12 May 2005 09:07:02 +0900

David Airey wrote: 

In Prism 4 (graphpad.com) there is the option of fitting curves using  
global curve fitting, in which parameters are shared. This is in a  
pharmacology context, like saturation binding. I don't find anything  
searching for "global curve fitting" using Stata.

A quick description of global curve fitting in this context is:

http://www.graphpad.com/articles/P4Global.pdf

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

You just add another variable to the equation to identify the dataset for each 
curve.  In the first example given, it's a dummy (indicator) variable:  0 = 
control dataset and 1 = treated.  In the second example (Schild plot), the 
variable is the concentration of antagonist, which naturally occurs in the 
nonlinear equation, anyway.

It's the same for the remaining three examples.  The curves are fit conjointly, 
datasets contributing being identified by indicator or continuous 
(concentration) variable terms in the equations.

Joseph Coveney


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