[R] factors with multiple levels

Agnieszka Konopka agnieszka.e.konopka at gmail.com
Tue Dec 6 10:53:29 CET 2011

Hi R-experts,

I'm running into some trouble with a multi-level factor. My apologies
if this is a basic question, but I have been told there are different
ways to do this and would like to see what you think.

In the dataset I'm looking at, subjects named pictures multiple times
(e.g., they named each picture 8 times), so Repetition is a
multi-level factor. How would you enter it into a model? As a factor?
Or a numeric predictor? I understand the pros and cons of both
approaches, but there seems to be some debate about this. I am not
interested in the individual contrasts between different levels of the
Repetition factor, but only need the equivalent of an F value in a
standard ANOVA for that factor.

And what about dependencies between levels?

Many thanks in advance,


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