[R] Logistic regression: categorical predictor and continuous response

Christine Parent cparent at sfu.ca
Wed Jun 23 03:28:18 CEST 2004

Hi all,

I am fairly new to R, and not a stats expert. I am having trouble finding
information to help me analyzing my set of data.

I got morphological data on land snail shells of different species from the
Galapagos Islands. Each island has up to 6 different vegetation zones, and
snails have adapted to up to 4 of these zones on each of the major islands.

I would like to test if there is any correlation between the morphology of
the shells which is continuous (I ran a PCA analysis on the morphological
data, and the variation can be parted into two main principal components:
PC1 for size and PC2 for shape) and the vegetation zone where these snails
are found (which is a categorical predictor variable).

I believe I should run a logistic regression on this, but all I could find
in R was an analysis where the predictor was continuous and the response was
categorical. Could anyone direct me to the relevant ref or how to write the
proper script to run a logistic regression analysis where the predictor
would be categorical and the response continuous?

Any help or advice on this would be greatly appreciated!

Many thanks,

Christine Parent
Ph.D. candidate
Department of Biological Sciences
Simon Fraser University
cparent at sfu.ca

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