Have you read the Stata manuals? A good place to start would be the
User's Guide entry on "Obtaining robust variance estimates".
--Mark
> I have searched google and did not find much infomation.
> I would appreciate any suggestion on how to find out the right answer.
>
> Thank you,
>
> Alice
>
>
>
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Alice(Libo)
> Sun
> Sent: Wednesday, September 14, 2005 10:44 PM
> To: [email protected]
> Subject: st: Joint F test in the panel data when cluster option used
>
>
> Dear Statalist,
>
> I have a question regarding joint F tests for a panel data. Stata gives me
> different F tests if I add/drop cluster(ID) option.I wonder which one is
> correct. Does it vary to which model I use, OLS, ordered probit, logit?
>
> Appreciate your suggesion.
>
> The following is my example:
>
> The panel dataset contains 50 firms over 10 years. I run the following
> regression:
>
> "
> regress Y X1 x2 x3 x4, cluster(firmID)
>
> test x2 x3
> "
>
> Stata gives me result for F(2,49).
>
> Is that the wrong joint F test?
>
> If I drop cluster() option and run the above regression and tests, stata
> gives me F(2,495).
> Is that the right one?
>
>
> I tried ordered probit model for the panel data, stats gives me different
> chi2(2) with or without cluster() added.
>
> Thank you,
>
> Alice Sun
>
>
>
> *
> * For searches and help try:
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> *
> * For searches and help try:
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> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
Prof. Mark Schaffer
Director, CERT
Department of Economics
School of Management & Languages
Heriot-Watt University, Edinburgh EH14 4AS
tel +44-131-451-3494 / fax +44-131-451-3294
email: [email protected]
web: http://www.sml.hw.ac.uk/ecomes
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*
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