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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: Interpreting Poisson regression results with squared term |

Date |
Wed, 13 Aug 2008 16:55:23 +0100 |

In addition, the position of the turning point on the quadratic of Y in X1 given X2 and X3 can be derived easily. That may or may not have a substantive interpretation. Nick n.j.cox@durham.ac.uk Maarten buis --- Antonio Silva <asilva100@live.com> wrote: > I ran a Poisson regression in which # of groups founded per year was > the dependent variable. My independent variables of interest are X1 > and X1-squared. For these non-linear effects in non-linear models I prefer to show graphs, in this case of the predicted rate against X1. For these kinds of graphs -adjust- is your friend, see the example below. The key trick is to specify in the -adjust- command -by(X1)-, in this case -by(ment)-, and not mentioning the square term. This way for each value of X1/ment the mean of the square term is used in the computation, which is the value of X1/ment squared. *---------------------- begin example -------------------- // get data net from http://www.stata-press.com/data/lf2/ net get rmcdvs // start the analysis use couart2, clear gen ment2 = ment^2 poisson art fem mar kid5 phd ment ment2 adjust fem=0 mar=1 kid5=1 phd , by(ment) exp replace ci twoway rarea lb ub ment || /// line exp ment, /// lpattern(solid) legend(off) /// ytitle(rate) *------------------------ end example --------------------- (For more on how to use examples I sent to the Statalist, see http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html ) * * 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/

**References**:**st: Interpreting Poisson regression results with squared term***From:*Antonio Silva <asilva100@live.com>

**Re: st: Interpreting Poisson regression results with squared term***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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