[R] ANOVA/aov question

[eph1v3t8-rhls6783@mailblocks.com]

I'm a bit confused about the anova/aov functions.  Both seem to rely on 
data models, where the relationship between the dependent variables and 
the independent variables can be expressed as a formula.  In what I am 
trying to do, all of my independent variables are qualitative, not 
quantitative.  For example, for each of two options, "option A" and 
"option B" I have collected a set of measurements of the same quantity, 
and I wish to do an ANOVA test to see if that factor (actually I have 
three factors, with 2 levels each) has a significant influence on the 
measured quantity.

Can R be used for this kind of ANOVA, or must the independent variables 
be quantitative in nature?  If the answer is that it can be done, and 
that it can be done with anova/aov, how do I go about expressing the 
"data model" for qualitative factors?

Thanks much,
    --Paul

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