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RE: R: st: qladder


From   Ozgur Ozdemir <ozdemirozgur@hotmail.com>
To   Stata <statalist@hsphsun2.harvard.edu>
Subject   RE: R: st: qladder
Date   Thu, 22 Sep 2011 13:39:33 +0000


Hi Carlo,
sorry I put it wrong. ovtest results shows the indication of omitted variables, but all other tests seem fine including normal distribution of residuals, cook's d etc and i am not sure how I will resolve it? any help appropriated.




kind regards
Ozgur Ozdemir



----------------------------------------
> From: carlo.lazzaro@tin.it
> To: statalist@hsphsun2.harvard.edu
> CC: ozdemirozgur@hotmail.com
> Subject: R: st: qladder
> Date: Thu, 22 Sep 2011 15:00:57 +0200
>
>
> Dear Ozgur,
> I do not understand your concern.
> If the -ovtest- does not reject the null hypothesis of no omitted variables,
> your regression model has no misspecification problems (ie, all the relevant
> explanatory variables are included in the RHS).
>
>
> Kindest Regards,
> Carlo
>
> -----Messaggio originale-----
> Da: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di Ozgur Ozdemir
> Inviato: giovedì 22 settembre 2011 13.57
> A: Stata
> Oggetto: RE: st: qladder
>
>
>
> Thanks Nic,
> you are right, in my case, residuals I think should be normally distributed
> and i am happy with it but when I run the ovtest, it does not reject the
> null hypothesis, that means, something is wrong with the transformations or
> interactions within the model, not sure if i really need to pass the ovtest.
> I did not see lots of papers reported ovtest results anyway.
>
>
>
>
>
> kind regards
> Ozgur
>
>
> ----------------------------------------
> > Date: Thu, 22 Sep 2011 12:52:31 +0100
> > Subject: Re: st: qladder
> > From: njcoxstata@gmail.com
> > To: statalist@hsphsun2.harvard.edu
> >
> > I don't think I can suggest a complete list for you. You need to look
> > at good publications in your field and talk to your
> > advisors/supervisors/committee about what is expected. The idea of a
> > link function is perhaps best covered in books on generalised linear
> > models which, to be frank, are from what you say likely to be a tough
> > read for you.
> >
> > That said, the purpose of -qladder- is to suggest transformations that
> > make data more nearly normal. However, it is not an assumption of
> > regression that data are normally distributed. Consider x = 1(1)10, y
> > = 2 + 3x. Here regression makes perfect sense and it is not a problem
> > that neither y nor x is normally distributed.
> >
> > Nick
> >
> > On Thu, Sep 22, 2011 at 12:42 PM, Ozgur Ozdemir
> > <ozdemirozgur@hotmail.com> wrote:
> > >
> > >
> > > Hi Nick,
> > > that is great, thanks, what kind of link functions? meanwhile, I am very
> new to Stata and just collected my data for my phd however still struggling
> with regression analysis. it seems, it will be difficult than what I
> expected. How can i find a complete list of activities to be done during a
> regression / step by step journey ? it seems, i am finding something new
> everyday. thanks in advance.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > kind regards
> > > Ozgur Ozdemir
> > > T: +44 (0) 75 0332 9865
> > > E: ozdemirozgur@hotmail.com<mailto:ozdemirozgur@hotmail.com>
> > > Skype : ozgurozdemir2005
> > >
> > >
> > > ----------------------------------------
> > >> Date: Thu, 22 Sep 2011 12:38:44 +0100
> > >> Subject: Re: st: qladder
> > >> From: njcoxstata@gmail.com
> > >> To: statalist@hsphsun2.harvard.edu
> > >>
> > >> It's enough that some are real zeros for the transformations concerned
> > >> to be invalid. That doesn't rule out using link functions that indulge
> > >> zeros.
> > >>
> > >> Nick
> > >>
> > >> On Thu, Sep 22, 2011 at 12:35 PM, Ozgur Ozdemir
> > >> <ozdemirozgur@hotmail.com> wrote:
> > >> >
> > >> > Hi Nic,
> > >> > It seems you are right, i have too many zeros but some of them are
> real zeros, and some of them are missing values. i am not sure how I can
> handle it.
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >> From: njcoxstata@gmail.com
> > >> >> To: statalist@hsphsun2.harvard.edu
> > >> >>
> > >> >> The implication is that you have zeros in your data so that the
> > >> >> transformations not plotted are not computable for all values. It is
> > >> >> thus not clear that you are missing anything that could be useful.
> > >> >>
> > >> >> Nick
> > >> >>
> > >> >> On Thu, Sep 22, 2011 at 12:18 PM, Ozgur Ozdemir
> > >> >> <ozdemirozgur@hotmail.com> wrote:
> > >> >>
> > >> >> > when I use the qladder command, it does show only four graphs
> including cubic, square, identity and square root. but does not show i.e
> inverse, 1/square and some others. Is there any way that I can get others
> graphed?
> > >> >> >
> >
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