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 one-sided 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
two-sided 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 two-sided and its
left had side variable is a factor, box-plots 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 lmList
plot(x, form, abline, id, idLabels, grid, ...)a diagnostic Trellis plot.
an object inheriting from class "lmList", representing
a list of lm objects with a common model.
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.
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.
an optional numeric value, or one-sided formula. If given as
a value, it is used as a significance level for a two-sided 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 one-sided 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.
an optional vector, or one-sided 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
one-sided 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).
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.
José Pinheiro and Douglas Bates bates@stat.wisc.edu
lmList,predict.lm,
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)
# box-plots of residuals by Subject
plot(fm1, Subject ~ resid(.))
# observed versus fitted values by Subject
plot(fm1, distance ~ fitted(.) | Subject, abline = c(0,1))
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