[R] Modality Test

[Mark Difford]

Hi Bert,

>> ## returns TRUE only if the distributions are the same ...

Thanks for the elegant code. Problem is, the result is elusive, constantly
slipping from view and then rolling into the dip. Perhaps it's broken in
this version of R (2.7.2.Patched). A fix would therefore be much
appreciated, as I may need to use it again in the near future. A little
example follows:

##
p1 <- rnorm(100, 10, 5)
p2 <- rnorm(100, 35, 5)
equaldist(p1, p2)
[1] FALSE
equaldist(c(p1,p2), c(p2,p1))
[1] FALSE

plot(density(c(p1, p2)), main="Twin Peaks")
lines(c(p1,p2))
?

Regards, Mark.


Bert Gunter wrote:
> 
> Here is a function that tests for equality of however many distributions
> as
> you like:
> 
> equaldist <- function(...){
> ## ... numeric sample vectors from the possibly different distributions to
> be tested
> ## returns TRUE only if the distributions are the same
> FALSE
> }
> 
> ;-)
> 
> -- Bert Gunter
> Genentech 
> 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On
> Behalf Of Mark Difford
> Sent: Tuesday, September 09, 2008 1:23 PM
> To: r-help at r-project.org
> Subject: Re: [R] Modality Test
> 
> 
> Hi Amin,
> 
> And I have just remembered that there is a function called curveRep in
> Frank
> Harrell's Hmisc package that might be useful, even if not quite in the
> channel of your enquiry. curveRep was added to the package after my
> struggles, so I never used it and so don't know how well it performs
> (quite
> well, I would think).
> 
> Regards, Mark.
> 
> 
> Amin W. Mugera wrote:
>> 
>> 
>> Dear Readers:
>> 
>> I have two issues in nonparametric statistical analysis that i need
>> help:
>> 
>> First, does R have a package that can implement the multimodality test,
>> e.g., the Silverman test, DIP test, MAP test or Runt test. I have seen
>> an earlier thread (sometime in 2003) where someone was trying to write
>> a code for the Silverman test of multimodality. Is there any other
>> tests that can enable me to know how many modes are in a distribution?
>> 
>> Second, i would like to test whether two distributions are equal. Does R
>> have a  package than can implement the Li (1996) test of the equality
>> of two distributions? Is there any other test i can use rather than the
>> Li test?
>> 
>> Thank you in advance for your help.
>> 
>> Amin Mugera
>> Graduate Student
>> AgEcon Dept. Kansas State University
>> 
>> ______________________________________________
>> 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.
>> 
>> 
> 
> -- 
> View this message in context:
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> 
> ______________________________________________
> 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.
> 
> ______________________________________________
> 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.
> 
> 

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