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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? > > >> >> > > > > > * > > * 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/ * * 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: qladder***From:*Ozgur Ozdemir <ozdemirozgur@hotmail.com>

**R: st: qladder***From:*"Carlo Lazzaro" <carlo.lazzaro@tin.it>

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