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From |
Carolina Lopez <carolina.univ@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: non linear equation difficulties with nl function evaluation program |

Date |
Wed, 25 Aug 2010 09:36:40 +0200 |

Hi Maarten, Thanks for your answer. The thing is that n is the number of cities were the operator is present using the same type of contract, so it varies by city and year. I already calculated this, and introduced it in the data as a variable, to then simplify estimations. I need it to be taken as a variable. Thanks Caorlina 2010/8/25 Maarten buis <maartenbuis@yahoo.co.uk>: > --- On Tue, 24/8/10, Carolina Lopez wrote: >> I am working on the estimation of this transport cost >> function, and getting issues with the func prog using nl: >> lcostratio= { [a(1+a+(n-2))] / [(1+a-k)(1+a+k(n-1)] } { >> b1lpko+b2lsalratio} - { [ak] / [ 1+a-k)(1+a+k(n-1)] } >> { b3sum_lpko + b4sum_lsalratio } + { [1+(n-1)k ] / >> [ [ 1+a+k(n-1)]} lna > > <snip> > >> I am not sure I am introducing n correctly here, since I do >> not expect a parameter, I just want it to feed data for my >> terms. > > I guess n is just the number of observations, you can access > that using _N, if you have missing values I would outside > the evaluator progam do something like > > count if !missing(var1, var2, ...) > global S_N = r(N) > > And than inside the evaluator program refer to n as $S_N. > > In general, the way to debug such a program is to simplify, > start with a very simple version of that function, get that > to work, add a parameter, get that to work, etc, etc. > > Hope this helps, > Maarten > > -------------------------- > Maarten L. Buis > Institut fuer Soziologie > Universitaet Tuebingen > Wilhelmstrasse 36 > 72074 Tuebingen > Germany > > http://www.maartenbuis.nl > -------------------------- > > > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: non linear equation difficulties with nl function evaluation program***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**References**:**st: non linear equation difficulties with nl function evaluation program***From:*Carolina Lopez <carolina.univ@gmail.com>

**Re: st: non linear equation difficulties with nl function evaluation program***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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