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Re: st: RE: f-test after -qreg- or -bsqreg-


From   Joseph Coveney <[email protected]>
To   Statalist <[email protected]>
Subject   Re: st: RE: f-test after -qreg- or -bsqreg-
Date   Tue, 13 Dec 2005 21:45:32 +0900

M. Haider Hussain wrote:

Errors were non-normally distributed, that's why I'm using -qreg-. In
other words, I'm not prepared to enforce CLRM assumptions.
[redacted]
> > . . . If I want to compute the joint significance
> > of the regressors, can I still use the F-test given by
> >
> > F=[r2/(k-1)]/[(1-r2)/(n-k)]
> >
> > If this isn't the case, what's the measure of joint significance of
> > the regressors after -qreg- / -bsqreg-?

--------------------------------------------------------------------------------

It seems that the answer to your first question is "no."  You can always
check that by a Monte Carlo experiment to see just what the test size is for
the formula after -bsqreg- under a joint null hypothesis.

As to your second question, what's the problem with using -test-, as Maarten
Buis recommended?

Joseph Coveney


Using the example in the online helpfile:

. sysuse auto
(1978 Automobile Data)

. bsqreg price weight length foreign, reps(400)
[output redacted]

. test weight length foreign

 ( 1)  weight = 0
 ( 2)  length = 0
 ( 3)  foreign = 0

       F(  3,    70) =    4.65
            Prob > F =    0.0051

. local r2 = 1 - e(sum_adev) / e(sum_rdev)

. local k = e(N) - e(df_r)

. display (`r2' / (`k' - 1) ) / ( ( 1 - `r2') / e(df_r) )
7.1577324


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