Diagnostic plots for the linear model fits corresponding to the
object
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. The expression
on the right hand side of the formula, before a `|' operator,
must evaluate to a data frame with at least two columns. If the data
frame has two columns, a scatter plot of the two variables is
displayed (the Trellis function
xyplot is used). Otherwise, if
more than two columns are present, a scatter plot matrix with
pairwise scatter plots of the columns in the data frame is displayed
(the Trellis function
splom is used).
an object inheriting from class
lmList, representing
a list of
lm objects with a common model.
OPTIONAL ARGUMENTS:
form
an optional one-sided formula specifying the desired type of
plot. Any variable present in the original data frame used to obtain
object can be referenced. In addition,
object 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. The expression on the right hand side of
form, and to
the left of the `|' operator, must evaluate to a data frame with
at least two columns. Default is `~ coef(...', corresponding to
a pairs plot of the coefficients of
object.
id
an optional numeric value, or one-sided formula. If given as
a value, it is used as a significance level for an outlier
test based on the Mahalanobis distances of the estimated random
effects. Groups with random effects distances greater than the
1-value percentile of the appropriate chi-square 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 points in the
plot. If missing, no points are identified.
idLabels
an optional vector, or one-sided formula. If given as a
vector, it is converted to character and used to label the
points 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
points. Default is the innermost grouping factor.
grid
an optional logical value indicating whether a grid should
be added to plot. Default is
FALSE.
subset
an optional expression indicating the subset of the
observations that should be used in the plot. This can be a logical
vector, or a numeric vector indicating which observation numbers
are to be included, or a character vector of the row names to be
included. All observations are included by default.
...
optional arguments passed to the Trellis plot function.
VALUE:
a diagnostic Trellis plot.
SEE ALSO:
,
,
EXAMPLES:
fm1 <- lmList(distance ~ age | Subject, Orthodont)
# scatter plot of coefficients by gender, identifying unusual subjects
pairs(fm1, ~coef(.) | Sex, id = 0.1, adj = -0.5)
# scatter plot of estimated random effects
pairs(fm1, ~ranef(.))