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From |
Lopa Chakraborti <lchakraborti@arec.umd.edu> |

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

Subject |
RE: st: FW: comparing xtregar coefficients across models |

Date |
Sat, 26 Feb 2011 08:18:24 -0500 |

Sorry, forgot to mention that I also reversed the order of running the two models i.e.- Run model 2. Save the beta in a scalar as: . scalar b_pastyearseaavgwq=_b[pastyearseaavgwq] Run model 1. Run test as: . test _b[lagseaavgwqfoia04avg3]=b_pastyearseaavgwq The test statistic shows that the two coefficients are not significantly different from each other, in both cases. So, can I conclude then that the coefficients are not statistically different? many thanks Lopa ________________________________________ From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of Lopa Chakraborti [lchakraborti@arec.umd.edu] Sent: Saturday, February 26, 2011 8:09 AM To: statalist@hsphsun2.harvard.edu Subject: RE: st: FW: comparing xtregar coefficients across models Thanks much for your advice. I actually came across this example on suest. But when I try to run suest after xtregar it gives me the error message that score variables are not available from my regression....to run the model with score option. I am afraid I need some advice on whether score option is available for xtregar. many thanks Lopa ________________________________________ From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of Christopher Baum [kit.baum@bc.edu] Sent: Saturday, February 26, 2011 6:46 AM To: statalist@hsphsun2.harvard.edu Subject: Re: st: FW: comparing xtregar coefficients across models <> On Feb 26, 2011, at 2:33 AM, Lopa wrote: > > The problem was that I was trying to test the equality of the two t-stats. Instead, I needed to use the coefficients generated by the two models for the test command. > > Run model 1. > Save the beta in a scalar as: > . scalar b_lagseaavgwqfoia04avg3=_b[lagseaavgwqfoia04avg3] > Run model 2. > Run test as: > . test _b[pastyearseaavgwq]=b_lagseaavgwqfoia04avg3 This makes no sense, and does not address the underlying problem of statistical inference. You are testing an estimated coefficient from the second model against a fixed number. That test assumes that the number from the first model is your hypothesized value of the coefficient, and completely ignores the sampling error associated with that coefficient estimate. The test you have run would make sense if the fixed number was some theory's prediction about that coefficient. I don't know if -suest- works in your context, but here is a valid test of a similar hypothesis with -regress-: sysuse auto,clear qui reg price mpg turn if foreign est sto f qui reg price mpg turn if !foreign est sto d suest f d test [f_mean]turn = [d_mean]turn Kit Baum | Boston College Economics & DIW Berlin | http://ideas.repec.org/e/pba1.html An Introduction to Stata Programming | http://www.stata-press.com/books/isp.html An Introduction to Modern Econometrics Using Stata | http://www.stata-press.com/books/imeus.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/ * * 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/

**References**:**Re: st: FW: comparing xtregar coefficients across models***From:*Christopher Baum <kit.baum@bc.edu>

**RE: st: FW: comparing xtregar coefficients across models***From:*Lopa Chakraborti <lchakraborti@arec.umd.edu>

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