View source: R/spreadLevelPlot.R
spreadLevelPlot | R Documentation |
Creates plots for examining the possible dependence of spread on level, or an extension of these plots to the studentized residuals from linear models.
spreadLevelPlot(x, ...)
slp(...)
## S3 method for class 'formula'
spreadLevelPlot(x, data=NULL, subset, na.action,
main=paste("Spread-Level Plot for", varnames[response],
"by", varnames[-response]), ...)
## Default S3 method:
spreadLevelPlot(x, by, robust.line=TRUE,
start=0, xlab="Median", ylab="Hinge-Spread",
point.labels=TRUE, las=par("las"),
main=paste("Spread-Level Plot for", deparse(substitute(x)),
"by", deparse(substitute(by))),
col=carPalette()[1], col.lines=carPalette()[2],
pch=1, lwd=2, grid=TRUE, ...)
## S3 method for class 'lm'
spreadLevelPlot(x, robust.line=TRUE,
xlab="Fitted Values", ylab="Absolute Studentized Residuals", las=par("las"),
main=paste("Spread-Level Plot for\n", deparse(substitute(x))),
pch=1, col=carPalette()[1], col.lines=carPalette()[2:3], lwd=2, grid=TRUE,
id=FALSE, smooth=TRUE, ...)
## S3 method for class 'spreadLevelPlot'
print(x, ...)
x |
a formula of the form |
data |
an optional data frame containing the variables to be plotted.
By default the variables are taken from the environment from which
|
subset |
an optional vector specifying a subset of observations to be used. |
na.action |
a function that indicates what should happen when the data contain |
by |
a factor, numeric vector, or character vector defining groups. |
robust.line |
if |
start |
add the constant |
main |
title for the plot. |
xlab |
label for horizontal axis. |
ylab |
label for vertical axis. |
point.labels |
if |
las |
if |
col |
color for points; the default is the first entry
in the current car palette (see |
col.lines |
for the default method, the line color, defaulting to the second entry in the car color palette;
for the |
pch |
plotting character for points; default is |
lwd |
line width; default is |
grid |
If TRUE, the default, a light-gray background grid is put on the graph |
id |
controls point identification; if |
smooth |
specifies the smoother to be used along with its arguments; if |
... |
arguments passed to plotting functions. |
Except for linear models, computes the statistics for, and plots, a Tukey spread-level plot of log(hinge-spread) vs. log(median) for the groups; fits a line to the plot; and calculates a spread-stabilizing transformation from the slope of the line.
For linear models, plots log(abs(studentized residuals) vs. log(fitted values). Point labeling was added in November, 2016.
The function slp
is an abbreviation for spreadLevelPlot
.
An object of class spreadLevelPlot
containing:
Statistics |
a matrix with the lower-hinge, median, upper-hinge, and hinge-spread
for each group. (Not for an |
PowerTransformation |
spread-stabilizing power transformation, calculated as |
John Fox jfox@mcmaster.ca
Fox, J. (2016) Applied Regression Analysis and Generalized Linear Models, Third Edition. Sage.
Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.
Hoaglin, D. C., Mosteller, F. and Tukey, J. W. (Eds.) (1983) Understanding Robust and Exploratory Data Analysis. Wiley.
hccm
, ncvTest
spreadLevelPlot(interlocks + 1 ~ nation, data=Ornstein)
slp(lm(interlocks + 1 ~ assets + sector + nation, data=Ornstein))
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