[R] Nested design with aov

Prof Brian Ripley ripley at stats.ox.ac.uk
Sat Mar 4 13:50:17 CET 2000


> Date: Sat, 04 Mar 2000 12:19:46 +0000
> From: Marcelo Martinez Palao <marmp at fcu.um.es>
> 
> 
> I want to do this model:
> 
> Y_ml=Mu+M+L(M)+Error
> 
> M is a fixed factor with two levels, 1 and 2
> L is a random factor and nested in M, with 9 levels (9 places inside
> each level of M)

L and M appear to be sets of numbers, not R factors, and you have not
declared L to be random.

> M <- factor(rep(1:2, rep(27, 2)))
> L <- factor(rep(1:18, rep(3, 18)))
> summary(aov(amarc ~ M + M/L))
            Df  Sum Sq Mean Sq F value    Pr(>F)
M            1 130.667 130.667 35.2800 8.366e-07
M:L         16 313.259  19.579  5.2863 1.682e-05
Residuals   36 133.333   3.704                  

If you really want L to be random, you will need to used a Error term.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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