[R] discriminant function analysis

[Gavin Simpson]

On Tue, 2010-11-16 at 12:01 -0500, Mike Gibson wrote:
> My objective is to look at differences in two species of fish from
> morphometric measurements.  My morphometric measurements are head
> length, eye diameter, snout length, and measurements from tail to each
> fin. I want to use discrimanant function analyis to determine if there
> are differences between the two species.  
>  
> I am familiar with R but new to discrimannt function analysis.  I want
> to learn how to run this analysis in R.  My internet search has not
> been very successful.  I did see refrence of the linear discriminant
> function (lda) in R but I am not sure if this is the correct function
> for me.  

With nothing further to go on, yes, use lda() in package MASS. It will
find linear combinations of your morphometric variables that best
discriminate between your two species of fish (i.e best separate the
species).

> Any advice and especially a reference to any examples would be greatly
> appreciated.  

require(MASS)
mod <- lda(Species ~ ., data = iris)
mod
plot(mod)
plot(mod, dimen = 1)

You might also be inclined to buy/track down this book:

http://www.springer.com/statistics/life+sciences,+medicine+%26
+health/book/978-0-387-77789-4

which is in the UseR series from Springer on morphometric analysis using
R. If you choose to buy, note that there is a 20% discount if you grab
the code from the Books page on the R website and register with
Springer.

G

> Thanks.  
>  
> Mike  		 	   		  
> 	[[alternative HTML version deleted]]
> 
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