p.res.2fact {sfsmisc}

Plot Numeric (e.g. Residuals) vs 2 Factors Using Boxplots

Description

Plots a numeric “residual like” variable against two factor covariates, using boxplots.

Usage

p.res.2fact(x, y, z, restricted, notch = FALSE,
            xlab = NULL, ylab = NULL, main = NULL)

Arguments

x, y

two factors or numeric vectors giving the levels of factors.

z

numeric vector of same length as x and y, typically residuals.

restricted

positive value which truncates the size. The corresponding symbols are marked by stars.

notch

logical indicating if the boxplots should be notched, see boxplot(*,notch).

xlab, ylab

axis labels, see plot.default, per default the actual argument expressions.

main

main title passed to plot, defaulting to the deparsed z argument.

Details

if values are restricted, this make use of the auxiliar function u.boxplot.x.

Author(s)

Lorenz Gygax [e-mail] and Martin Maechler, Jan.95; starting from p.res.2x().

See Also

p.res.2x, boxplot, plot.lm, TA.plot.

Examples

I <- 8; J <- 3; K <- 20
xx <- factor(rep(rep(1:I, rep(K,I)),J))
yy <- factor(rep(1:J, rep(I*K,J)))
zz <- rt(I*J*K, df=5) #-- Student t with 5 d.f.
p.res.2fact(xx,yy,zz, restr= 4, main= "i.i.d. t <- 5 random  |.| <= 4")
mtext("p.res.2fact(xx,yy,zz, restr= 4, ..)",
      line=1, adj=1, outer=TRUE, cex=1)

## Real data
data(warpbreaks)
(fm1 <- lm(breaks ~ wool*tension, data = warpbreaks))
## call via formula method of p.res.2x():
p.res.2x(~ ., fm1) # is shorter than, but equivalent to
## p.res.2x(~ wool + tension, fm1)  ##  or the direct
## with(warpbreaks, p.res.2fact(wool, tension, residuals(fm1)))
##
## whereas this is "transposed":
p.res.2x(~ tension+wool, fm1)