[R] Tukey.aov with split-plot designs

Peter B. Mandeville mandevip at uaslp.mx
Wed Jul 5 08:29:58 CEST 2000

I am using R 1.1 with Redhat 6.2 and RW 1.001 with Win98 (the upkey doesn't
work on my IBM either as has been previously reported by others).

The function aov doesn't return either the residuals or the residual
degrees of freedom for split-plot designs. 

If you use the following code from Baron and Li's "Notes on the use of R
for psycology experiments and questionnaires"

data <- c(30,14,24,38,26,28,18,20,34,28,16,10,18,20,14,34,22,30,44,30)
Stv.df <-
res0 <- aov(rt~drug,data=Stv.df)
res1 <- aov(rt~drug+subj,data=Stv.df)
res2 <- aov(rt~drug+Error(subj/drug),data=Stv.df)

res0$resid works
resid(res0) works
res0$df.residual works

res1$resid works
resid(res1) works
res1$df.residual work

res2$resid doesn't work and reports NULL
resid(res2) doesn't work and reports NULL
res2$df.residual doesn't work and reports NULL

Is this an undocumented feature or an error?

It sure plays havoc with Dr. Bates' contribution of Tukey.aov which works
with res0 and res1 but doesn't work with res2 and reports 

Error in qtukey(p, nranges, nmeans, df, lower.tail, log.p) :
        Non-numeric argument to mathematical function

A simple but inelegant workaround is to input mse and df.residual as
function arguments in addition to the aov object. Does anyone have a better

Thank you,

Peter B.

Peter B. Mandeville                             mandevip at deimos.tc.uaslp.mx
Jefe del Depto. de Informática y Bioestadística rpe1531 at pasteur.fmed.uaslp.mx 
Facultad de Medicine                            Tel: 48 26-23-45 ext. 232
Universidad Autónoma de San Luis Potosí         Fax: 48 28-23-52
Av. V. Carranza 2405
Col. Los Filtros
Apartado Postal 145
San Luis Potosí, S.L.P.
78210 México

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