[R] curve comparison

[David Winsemius]

On Jul 30, 2012, at 8:48 PM, arun wrote:

> Hi,
>
> Please check this article which details the method for comparison:
>
> Statistica Sinica 17(2007), 1115-1137
> TESTING FOR THE EQUALITY OF k REGRESSION
> CURVES
> Juan Carlos Pardo-Fern ́ndez, Ingrid Van Keilegom and Wenceslao  
> Gonz ́lez-Manteiga
>
> Also, check some examples (http://www.stat.umn.edu/geyer/old/5601/examp/kolmogorov.html 
> ).

Thanks, AK for that link. Geyer's heuristic explanation helps me  
better understand the underpinnings of the KS test.

>
> I am not very familiar with non-parametric tests.
>
> A.K
> ________________________________
> From: Luis Fernando García Hernández <luysgarcia at gmail.com>
> To: arun <smartpink111 at yahoo.com>
> Sent: Monday, July 30, 2012 9:00 PM
> Subject: Re: [R] curve comparison
>
> Thanks both for your answer,
>
> Will, do you have any reference which shows me how  how to perform  
> this analysis? I´d like to know  to find out how to do it. In my  
> case data is similar to compare several diversity curves, I do not  
> know if you are familiar with them.

I wish I knew what a "diversity curve" was. You say below that these  
curves are from regression procedures, so there are probably  
theoretical results that would support a more statistically powerful  
procedure than resorting to KS tests.

Two points:
--- You may get a more knowledgeable audience in one of the SIG  
mailing lists.
	https://stat.ethz.ch/mailman/listinfo/r-sig-epi
	https://stat.ethz.ch/mailman/listinfo/r-sig-phylo

--- If you want non-ecologists to help, you will need to provide some  
examples that better document what procedures you have been using.

-- 
David.

>
> Related to the Kolmogrov Smirnov test, I´ll try, I did not know it  
> allowed curve comparison.
>
> This is a great space to share questions, so thanks both for your  
> answer!
>
>
> 2012/7/30 arun <smartpink111 at yahoo.com>
>
> Hello,
>>
>> You could try some non-parametric tests for comparison such as  
>> Kolmogorov-Smirnov test (ks.test() package: truncgof)or Cramer-von  
>> Mises test (cvmts.pval() package: CvM2SL2Test).
>>
>> A.K.
>> ----- Original Message -----
>> From: Luis Fernando García Hernández <luysgarcia at gmail.com>
>> To: r-help at r-project.org
>> Cc:
>> Sent: Monday, July 30, 2012 1:38 AM
>> Subject: [R] curve comparison
>>
>> Dear R users,
>>
>> I have seven regression lines I´d like to compare, in order to find  
>> out if
>> these are significatively different. The main problem is that these  
>> are
>> curves,  non normal, non homogeneous data, I´ve tried to linearize  
>> them but
>> it has not worked. So I´d like to know if you know any command or  
>> source in
>> R which explains how to perform this kind of comparison.
>>
>> Thanks in advance for your help!
>>
>>     [[alternative HTML version deleted]]
>>

David Winsemius, MD
Heritage Laboratories
West Hartford, CT