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. 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).
# S3 method for lmList
pairs(x, form, label, 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 one-sided 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. 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 x.
an optional character vector of labels for the variables in the pairs plot.
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.
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.
an optional logical value indicating whether a grid should
be added to plot. Default is FALSE.
optional arguments passed to the Trellis plot function.
José Pinheiro and Douglas Bates bates@stat.wisc.edu
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 -- "bivariate Gaussian (?)"
pairs(fm1, ~ranef(.))
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