[R] Simple qqplot question

[Joris Meys]

Also take a look at qq.plot in the package "car". Gives you exactly
what you want.
Cheers
Joris

On Fri, Jun 25, 2010 at 12:55 AM, Ralf B <ralf.bierig at gmail.com> wrote:
> More details...
>
> I have two distributions which are very similar. I have plotted
> density plots already from the two distributions. In addition,
> I created a qqplot that show an almost straight line. What I want is a
> line that represents the ideal case in which the two
> distributions match perfectly. I would use this line to see how much
> the errors divert at different stages of the plot.
>
> Ralf
>
>
>
> On Thu, Jun 24, 2010 at 5:56 PM, stephen sefick <ssefick at gmail.com> wrote:
>> You are going to have to define the question a little better.  Also,
>> please provide a reproducible example.
>>
>> On Thu, Jun 24, 2010 at 4:44 PM, Ralf B <ralf.bierig at gmail.com> wrote:
>>> I am a beginner in R, so please don't step on me if this is too
>>> simple. I have two data sets datax and datay for which I created a
>>> qqplot
>>>
>>> qqplot(datax,datay)
>>>
>>> but now I want a line that indicates the perfect match so that I can
>>> see how much the plot diverts from the ideal. This ideal however is
>>> not normal, so I think qqnorm and qqline cannot be applied.
>>>
>>> Perhaps you can help?
>>>
>>> Ralf
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
>>
>> --
>> Stephen Sefick
>> ____________________________________
>> | Auburn University                                   |
>> | Department of Biological Sciences           |
>> | 331 Funchess Hall                                  |
>> | Auburn, Alabama                                   |
>> | 36849                                                    |
>> |___________________________________|
>> | sas0025 at auburn.edu                             |
>> | http://www.auburn.edu/~sas0025             |
>> |___________________________________|
>>
>> Let's not spend our time and resources thinking about things that are
>> so little or so large that all they really do for us is puff us up and
>> make us feel like gods.  We are mammals, and have not exhausted the
>> annoying little problems of being mammals.
>>
>>                                                                -K. Mullis
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Joris Meys
Statistical consultant

Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

tel : +32 9 264 59 87
Joris.Meys at Ugent.be
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