[R] Problem Replicating Venables & Riply Split-Plot Example

rab rab at nauticom.net
Sat Feb 22 22:00:04 CET 2003

I'm using R 1.6.1 under Redhat Linux 8.0. I'm following the example from 
V&R (1994) pp. 177-181. I get the split-plot ANOVA table:

 > summary(oats.aov)

Error: B
          Df  Sum Sq Mean Sq F value Pr(>F)
Residuals  5 15875.3  3175.1

Error: B:V
          Df Sum Sq Mean Sq F value Pr(>F)
V          2 1786.4   893.2  1.4853 0.2724
Residuals 10 6013.3   601.3

Error: Within
          Df  Sum Sq Mean Sq F value    Pr(>F)
Nf         3 20020.5  6673.5 37.6856 2.458e-12 ***
Nf:V       6   321.7    53.6  0.3028    0.9322
Residuals 45  7968.7   177.1
Signif. codes:  0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1

I need to get hold of the residuals and fitted values. The usual way of 
using "resid" and "fitted" doesn't work I guess because this is a 
multistratum model. The "studres" function shows up if I load the MASS 
library. But I cannot get the "proj" and "update" functions to work as 
they do in S-Plus:

 > oats.fm <- update(oats.aov,qr=TRUE)
Error in update.default(oats.aov, qr = TRUE) :
        need an object with call component

How can I get the residuals and fitted values? Wouldn't there be three 
sets of residuals? One for the blocks (6 residuals), one for the 
varieties (18 resduals), and another for the subplots (72 residuals)? If 
we only looked at the varieties and blocks, this would be a randomized 
block design using the average for each plot as the observations. There 
would be 18 residuals. The F-statistic and p-value match the split-plot 
ANOVA results for variety.


Rick B.

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