[R] anova

[Peter Dalgaard BSA]

"Anna  H. Pryor" <anna at ptolemy.arc.nasa.gov> writes:

> I looked at the Introduction to R and am still confused.  Would it be possible 
> to ask a question in which I have three vectors and I want to perform an 
> anova on them.  Say A,B, and C.  Is there a standard form that I could use in 
> lm to get a model that I could use in anova?  Do I need to know more about my 
> problem?
> 
> I really appreciate any help in this.

There are many forms of anova. The type you describe, I presume, is
data from three separate groups, aka one-way ANOVA. You need to first
force your data into the parallel-vector layout like this

  y <- c(A,B,C)
  group <- factor(rep(1:3,c(7,9,13))) # provided there are 7 elements
                                      # in A, 9 in B and 13 in C

and then 

anova(lm(y~group))

or, for some more options, consider

oneway.test(y~group)



-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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