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Re: st: qladder


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: qladder
Date   Thu, 22 Sep 2011 12:52:31 +0100

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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