[R] newbie (me) needs to model distribution as two overlapping gaussians

[Greg Snow]

The mixreg package may help.  Just fit an intercept only model to your
data (may need to have x be a column of 1's and tell it not to include
an intercept) and see if it finds your mixtures.

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111
 
 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of tcornulier
> Sent: Monday, February 18, 2008 12:48 PM
> To: mmiller at mail.usp.edu
> Cc: r-help at r-project.org
> Subject: Re: [R] newbie (me) needs to model distribution as 
> two overlapping gaussians
> 
> Is a finite mixture of 2 gaussians the name you are looking for?
> This specific model will not deal with your N component however.
> 
> you can find some functions here:
> http://cran.r-project.org/web/views/Cluster.html
> 
> Thomas
> 
> mmiller at mail.usp.edu wrote:
> > Recently, I have been working with some data that look like two 
> > overlapping gaussian distributions.  I would like to either
> > 
> > 1) determine the mean and SD for each of the two distributions
> > 
> > OR
> > 
> > 2) get some (bayesian ?) statistic that estimates how likely an 
> > observation is to belong to the left-hand or right-hand distribution
> > 
> > In case I'm using the wrong language, my data looks 
> something like this:
> > 
> > B <- rnorm(500,40,10)
> > H <- rnorm(500,80,5 )
> > N <- runif(200,0,99)
> > D <- c(B,H,N)
> > 
> > Where B=background, H=hits, N=noise, and D=my observed distribution
> > 
> > I have seen analyses like this in the past, but I can't 
> remember what it is called.  If somebody out there can point 
> me towards an R function, or even the cannonical name for 
> this kind of model, I think I can write the necessary code.
> > 
> > Thanks in advance,
> > Mark
> > 
> > ______________________________________________
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> > PLEASE do read the posting guide 
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> > 
> 
> -- 
> 
> 
> **************************
> Thomas Cornulier
> 
> Mammal Research Institute
> Polish Academy of Sciences
> ul. Waszkiewicza 1c
> 17-230 Bialowieza
> http://www.zbs.bialowieza.pl/?en
> 
> tel (0048) 85 682 77 88
> 
> ______________________________________________
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> PLEASE do read the posting guide 
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> and provide commented, minimal, self-contained, reproducible code.
>