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Re: st: Stata command for parameter calculation with least square method?


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Stata command for parameter calculation with least square method?
Date   Thu, 1 Mar 2007 11:05:38 +0000 (GMT)

looks to me like a problem for -nl-, see: -help nl-

Hope this helps,
Maarten

--- Tobias Pfaff <tobiaspfaff@gmx.net> wrote:

> Hi,
> 
> for given data points I want to find out a parameter for a function
> such
> that the function fits best to the data points.
> The function would be: f(x)=x^alpha.
> The data points are:
> 
> x_values	y_values
> --------	--------
> 0,0000	0
> 0,0156	0,45
> 0,0313	0,52
> 0,0625	4,83
> 0,0938	11,66
> 0,1250	12,79
> 0,1875	21,5
> 0,2188	25,69
> 0,2344	27,89
> 0,2500	29,93
> 
> I know how I could do that with the least square method and the Excel
> solver.
> Which Stata command would deliver the same result? Is _reg3_ the
> appropriate
> command? How would the command line look like?
> 
> Furthermore, I want to do the same with 2 unknown parameters, e.g.
> for the
> function f(x)=-k*(-x)^alpha. Which command would be appropriate for 2
> unknown parameters (here: k and alpha)?
> 
> Any comments would be greatly appreciated.
> 
> Cheers,
> Tobias Pfaff
> 
> University of Muenster
> Germany
> 
> *
> *   For searches and help try:
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> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
> 


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

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


		
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