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From |
Maarten Buis <maartenlbuis@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: conception confusion - "fixed effects" and time effect on data with time factor |

Date |
Mon, 24 Oct 2011 10:25:38 +0200 |

On Fri, Oct 21, 2011 at 10:56 PM, House Wang <jwanghouse@gmail.com> wrote: > I think I have learned something from your response. "models are > supposed to be useful, not true." This is the most important of the > discussion. Thank you very much. Just to be sure: I am not claiming authorship. It is a loosely based on George Box's "all models are wrong, but some are useful" > For the model, I want to measure the maturity of an institution in > manipulating rules, which are supposed to increase across years. > Proximately, it is like a kid grow up. This is why I use year as a > trend variable. Two comments: 1) Calender time is wrong here. To answer such a question you need the age of the institution. You said earlier that age is not in the dataset, but if you have the date when the institution was founded and the time of the interview, you can trivially add age to your dataset by -gen age = interview_date - founding_date-. If you have only one instition than this won't matter much. However, if you are following multiple institutions with different founding dates, than this will be very important. 2) If you think of a process like growing up or maturing of an institution than that process will definately not be linear. So I would suggest you look into things like splines (-help mkspline-) or fractional polynomials (-help fracpoly-) to model age. 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/

**References**:**st: conception confusion - "fixed effects" and time effect on data with time factor***From:*House Wang <jwanghouse@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*Richard Williams <richardwilliams.ndu@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*House Wang <jwanghouse@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*Maarten Buis <maartenlbuis@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*House Wang <jwanghouse@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*Maarten Buis <maartenlbuis@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*House Wang <jwanghouse@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*Maarten Buis <maartenlbuis@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*House Wang <jwanghouse@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*Maarten Buis <maartenlbuis@gmail.com>

**Re: st: conception confusion - "fixed effects" and time effect on data with time factor***From:*House Wang <jwanghouse@gmail.com>

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