residual.plots {alr3}R Documentation

Residual plots and curvature tests for linear model fits

Description

Plots the residuals versus each term in a mean function and versus fitted values. Also computes a curvature test for each of the plots by adding a quadratic term and testing the quadratic to be zero. This is Tukey's test for nonadditivity when plotting against fitted values.

Usage

### This is a generic function with only one required argument:

residual.plots (m, ...)

### When the first argument is a linear model (of class lm), the form of the
### function is

residual.plots.lm(m,tukey=TRUE,exclude=NULL,plot=TRUE,
     layout=NULL,ask,...)

### The following are three related functions:    

resplot(m,varname="tukey",type="pearson",
                    plot=TRUE,add.quadratic=TRUE,
                    ylab=paste(string.capitalize(type),"Residuals"),...)
                    
resid.curv.test(m,varname)

tukey.nonadd.test(m)

Arguments

m lm regression object
tukey If TRUE, draw plot of residuals versus fitted values and compute Tukey's test of non-additivity.
exclude A list of predictor numbers for which plots will NOT be drawn. If NULL, all plots are drawn.
layout If set to a value like c(1,1) or c(4,3), the layout of the graph will have this many rows and columns. If not set, the program will select an appropriate layout. If the number of graphs exceed nine, you must select the layout yourself, or you will get a maximum of nine per page.
ask If TRUE, ask the user before drawing the next plot; FALSE if don't ask.
... residual.plots passes these arguments to resplot. resplot passes them to plot.
varname Quoted variable name for the horizontal axis, "tukey" by default for Tukey's test and the plot versus fitted values.
type Type of residuals to be used. Pearson residuals are appropriate for lm objects since there are equivalent to ordinary residuals with ols and correctly weighted residuals with wls.
ylab
add.quadratic if TRUE, fits the quadratic regression of the vertical axis on the horizontal axis.
plot If TRUE, draw the plot(s).

Details

resplot draws ONE residual plot and returns the curvature test and its significance level. residual.plots draws all residuals plots, versus each term in the model and versus fitted values, and returns all the curvature tests. residual.plots should not be used with factors. resid.curv.test computes the curvature test only.

Value

Returns a data.frame with one row for each plot drawn, one column for the curvature test statistic, and a second column for the corresponding p-value. This function is used primarily for its side effect of drawing residual plots.

Author(s)

Sanford Weisberg, sandy@stat.umn.edu

References

S. Weisberg (2005), Applied Linear Regression, third edition, Wiley, Chapter 8

See Also

See Also lm

Examples

data(highway)
highway$Sigs <- (round(highway$Sigs*highway$Len)+1)/highway$Len
attach(highway)
d <- data.frame(Rate=Rate,logLen=logb(Len,2),
                logADT=logb(ADT,2),logTrks=logb(Trks,2),
                Slim=Slim,Shld=Shld,logSigs1=logb(Sigs,2))
attach(d)
m2 <- lm(Rate~logLen+logADT+logTrks+Slim+Shld+logSigs1,d)
residual.plots(m2)

[Package alr3 version 1.0.9 Index]