RE: st: qladder

[Ozgur Ozdemir <ozdemirozgur@hotmail.com>]

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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