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re: st: Interpreting Non-Linear Least Squares


From   "Airey, David C" <david.airey@vanderbilt.edu>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   re: st: Interpreting Non-Linear Least Squares
Date   Sat, 23 Apr 2011 10:58:02 -0500

.



> [...] can anyone give me some clues on how to read this?
> 
> Thanks a lot,
> 
> Stefan Nijssen


I'm not sure what you are asking. Are you asking if the built in exp3 function is what you want? You can use different functions if your data don't fit the short list of common functions in help nl. If you want to know how various changes in parameters change the shape of the function you are using, try graphing changes in each parameter while holding the other constant, using the Stata -graph twoway function- command. You will want to also graph your model prediction (fitted values, see help predict) against your data to inspect fit, and look at the distribution of residuals for runs of positive or negative values. You may want to fit a family of closely related nonlinear functions and compare fits.

-Dave
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