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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: dummy variable |

Date |
Fri, 16 Sep 2011 12:26:27 +0200 |

I guess any intro stats/econometrics book that discusses regression will do, e.g Gujarati (1995) "Basic Econometric, third edition, MacGraw-Hill, page 71. (This tells you when I had my intro statistics/econometrics class...) -- Maarten On Fri, Sep 16, 2011 at 12:06 PM, Jing Zhou <jing.zhou@rmit.edu.au> wrote: > Thanks a lot, Maarten. your suggestions are very appreciated. Can you > please provide the reference of "The consequence of the fact that there > are so few 1s is that the variance of the variable will be low, and thus > the precision with which the effect of that variable is measured will > also be low, i.e. large standard errors and confidence intervals."? > > Regards, > Jing > > > > >>>> Maarten Buis <maartenlbuis@gmail.com> 16/09/11 7:30 下午 >>> > If you want to get results that control for that than you should add > that variable, otherwise you should not do so. If you want to add that > variable I would first try to find out why they are missing. For > example, is there only one shareholder, and is it thus impossible for > anyone to be the second largest shareholder or is the second largest > shareholder unknown. In the former case you can set those missing > values at zero (and possible add a dummy variable for single > shareholder), while in the latter case you can think of multiple > imputation (see: -help mi-). > > The consequence of the fact that there are so few 1s is that the > variance of the variable will be low, and thus the precision with > which the effect of that variable is measured will also be low, i.e. > large standard errors and confidence intervals. > > Hope this helps, > Maarten > > On Fri, Sep 16, 2011 at 10:51 AM, Jing Zhou <jing.zhou@rmit.edu.au> > wrote: >> Thanks Maarten, it measues whether the second largest shareholder of a >> listed company is a state shareholder. >> >> Jing >> >> >>>>> Maarten Buis <maartenlbuis@gmail.com> 16/09/11 6:02 下午 >>> >> On Fri, Sep 16, 2011 at 2:09 AM, Jing Zhou wrote: >>> I have a sample period from 2000-2009. now I am considering to add a >> dummy variable into the regression. for the year of 2009, only 24 out > of >> 550 observations (<5%) valued at 1 of this dummy. for 2008, 31 out of >> 502 observations (<5%) valued at 1. further, for the year of > 2000-2002, >> the missing value rate is 61.19%, 31.91%, and 13.33%, respectively. > for >> other variables of the regression, i can get relatively complete data >> value of each observation. therefore, is it still necessary to include >> this dummy in my regression? thanks! >> >> What is this dummy variable supposed to measure? >> >> -- 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/ >> > > > > -- > -------------------------- > 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/ > -- -------------------------- 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**:**Re: st: dummy variable***From:*"Jing Zhou" <jing.zhou@rmit.edu.au>

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