[R] ANOVA in Randomized-complete blocks design

[January Weiner]

Ops, sorry.

OK, as you see, I am going through S&R and doing the examples using R.
I have a further question, on the nested ANOVA example from Box 10.1
(mosquito female wing lengths).  I made sure that the data is correct
:-) (data below).

I am not sure how to create in R a Model II nested ANOVA.
aov( wing ~ cage / female ) which is, I believe, a fixed effect nested
ANOVA where females are nested within cages produced the correct sum
of squares, but computates a different F value for the cage effect:

            Df  Sum Sq Mean Sq F value    Pr(>F)
cage         2  665.68  332.84  255.70 1.452e-10 ***
cage:female  9 1720.68  191.19  146.88 6.981e-11 ***
Residuals   12   15.62    1.30

(whereas in S&R, among cages F = 1.741; the rest is same).  The F
value for the cage:female effect is the same as in S&R.  Why do I get
a higly significant cage effect?

In S&R, the significance of the cage effect is done by F = MSamong /
MSsubgr = 332.84 / 191.19 = 1.74. In the R model, F = 255.70, and I do
not understand where this value comes from (at first I thought that it
is MSamong / MSerror = 332.84 / 1.3 = 256.0308).

I am confused...

How should I modify the model?

Another question: is there a way to automatically estimate the
variance components, or do I have to take the respective MS' and
calculate it myself?

Thanks,
January

OK, here is the data:

cage female wing
cage1 f1 58.5
cage1 f1 59.5
cage1 f2 77.8
cage1 f2 80.9
cage1 f3 84.0
cage1 f3 83.6
cage1 f4 70.1
cage1 f4 68.3
cage2 f1 69.8
cage2 f1 69.8
cage2 f2 56.0
cage2 f2 54.5
cage2 f3 50.7
cage2 f3 49.3
cage2 f4 63.8
cage2 f4 65.8
cage3 f1 56.6
cage3 f1 57.5
cage3 f2 77.8
cage3 f2 79.2
cage3 f3 69.9
cage3 f3 69.2
cage3 f4 62.1
cage3 f4 64.5

Cheers,
January

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