plot.lmList {nlme}  R Documentation 
Diagnostic plots for the linear model fits corresponding to the
x
components are obtained. The form
argument gives
considerable flexibility in the type of plot specification. A
conditioning expression (on the right side of a 
operator)
always implies that different panels are used for each level of the
conditioning factor, according to a Trellis display. If form
is a onesided formula, histograms of the variable on the right hand
side of the formula, before a 
operator, are displayed (the
Trellis function histogram
is used). If form
is
twosided and both its left and right hand side variables are
numeric, scatter plots are displayed (the Trellis function
xyplot
is used). Finally, if form
is twosided and its
left had side variable is a factor, boxplots of the right hand side
variable by the levels of the left hand side variable are displayed
(the Trellis function bwplot
is used).
## S3 method for class 'lmList': plot(x, form, abline, id, idLabels, grid, ...)
x 
an object inheriting from class lmList , representing
a list of lm objects with a common model. 
form 
an optional formula specifying the desired type of
plot. Any variable present in the original data frame used to obtain
x can be referenced. In addition, x itself
can be referenced in the formula using the symbol
"." . Conditional expressions on the right of a 
operator can be used to define separate panels in a Trellis
display. Default is resid(., type = "pool") ~ fitted(.) ,
corresponding to a plot of the standardized residuals (using a pooled
estimate for the residual standard error) versus fitted values.

abline 
an optional numeric value, or numeric vector of length two. If given as a single value, a horizontal line will be added to the plot at that coordinate; else, if given as a vector, its values are used as the intercept and slope for a line added to the plot. If missing, no lines are added to the plot. 
id 
an optional numeric value, or onesided formula. If given as
a value, it is used as a significance level for a twosided outlier
test for the standardized residuals. Observations with
absolute standardized residuals greater than the 1  value/2
quantile of the standard normal distribution are identified in the
plot using idLabels . If given as a onesided formula, its
right hand side must evaluate to a logical, integer, or character
vector which is used to identify observations in the plot. If
missing, no observations are identified.

idLabels 
an optional vector, or onesided formula. If given as a
vector, it is converted to character and used to label the
observations identified according to id . If given as a
onesided formula, its right hand side must evaluate to a vector
which is converted to character and used to label the identified
observations. Default is getGroups(x) .

grid 
an optional logical value indicating whether a grid should
be added to plot. Default depends on the type of Trellis plot used:
if xyplot defaults to TRUE , else defaults to
FALSE .

... 
optional arguments passed to the Trellis plot function. 
a diagnostic Trellis plot.
Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu
lmList
, xyplot
,
bwplot
, histogram
fm1 < lmList(distance ~ age  Subject, Orthodont) # standardized residuals versus fitted values by gender plot(fm1, resid(., type = "pool") ~ fitted(.)  Sex, abline = 0, id = 0.05) # boxplots of residuals by Subject plot(fm1, Subject ~ resid(.)) # observed versus fitted values by Subject plot(fm1, distance ~ fitted(.)  Subject, abline = c(0,1))