R help - Mar 2004 - Plot is lost when fitting block as error

G'day,

Plot doesn't seem to work when I specify block as an error term, but does 
if I load block into the model as the first factor (see code below).

Is there some way to make plot work with the fancier model specification?

Also, if anyone knows how to get SEDs for this model I would really like to 
know.


response<-c(rnorm(5,5,2),rnorm(5,12,2),rnorm(5,18,2),rnorm(5,12,2))
factor1<-factor(rep(c(1,2),each=10))
factor2 <- factor(rep(rep(c(1,2),each=5),2))
block<-gl(5,1,20)
model<-aov(response~factor1*factor2+Error(block))
plot(model)


#THE RESULT IS:

Error in plot.window(xlim, ylim, log, asp, ...) :
         need finite xlim values
In addition: Warning messages:
1: no finite arguments to min; returning Inf
2: no finite arguments to max; returning -Inf
3: no finite arguments to min; returning Inf
4: no finite arguments to max; returning -Inf

BUT IF YOU SPECIFY THE MODEL AS

model<-aov(response~block+factor1*factor2)

THEN PLOT(MODEL) WORKS AS EXPECTED.


Don.


Dr Don Driscoll
Lecturer in Biodiversity
School of Biological Sciences
Flinders University
GPO Box 2100
Adelaide SA 5001
(08) 8201 2165

You second fit is of class c("aov", "lm"), the first of
class "aovlist".
There is no way to plot a series of aov fits in different strata, but you
can plot aspects of the individual fits: there is an example in (MASS4,
p.284).

In your case there is only one stratum of interest and
plot(model[["Within"]]) ought to work, but for some reason plot.lm
calls
predict() to get the fitted values.  I am not sure that the lm method for
plot is appropriate for aov fits, though: in particular leverage (and
hence Cook's distance) is not usually of interest.

On Sun, 7 Mar 2004, Don Driscoll wrote:
> G'day,
> 
> Plot doesn't seem to work when I specify block as an error term, but
does
> if I load block into the model as the first factor (see code below).
> 
> Is there some way to make plot work with the fancier model specification?
> 
> Also, if anyone knows how to get SEDs for this model I would really like to
> know.
SEDs are what?
> response<-c(rnorm(5,5,2),rnorm(5,12,2),rnorm(5,18,2),rnorm(5,12,2))
> factor1<-factor(rep(c(1,2),each=10))
> factor2 <- factor(rep(rep(c(1,2),each=5),2))
> block<-gl(5,1,20)
> model<-aov(response~factor1*factor2+Error(block))
> plot(model)
> 
> 
> #THE RESULT IS:
> 
> Error in plot.window(xlim, ylim, log, asp, ...) :
>          need finite xlim values
> 
> BUT IF YOU SPECIFY THE MODEL AS
> 
> model<-aov(response~block+factor1*factor2)
> 
> THEN PLOT(MODEL) WORKS AS EXPECTED.
Does it?  It is not what I think is sensible.

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595