{graphics}R Documentation

Plot Univariate Effects of a 'Design' or Model


Plot univariate effects of one ore more factors, typically for a designed experiment as analyzed by aov(). Further, in S this a method of the plot generic function for design objects.

Usage, y = NULL, fun = mean, data = NULL, ...,
            ylim = NULL, xlab = "Factors", ylab = NULL,
            main = NULL, ask = NULL, xaxt = par("xaxt"),
            axes = TRUE, xtick = FALSE)


x either a data frame containing the design factors and optionally the response, or a formula or terms object.
y the response, if not given in x.
fun a function (or name of one) to be applied to each subset. It must return one number for a numeric (vector) input.
data data frame containing the variables referenced by x when that is formula like.
... graphical arguments such as col, see par.
ylim range of y values, as in plot.default.
xlab x axis label, see title.
ylab y axis label with a “smart” default.
main main title, see title.
ask logical indicating if the user should be asked before a new page is started – in the case of multiple y's.
xaxt character giving the type of x axis.
axes logical indicating if axes should be drawn.
xtick logical indicating if “ticks” (one per factor) should be drawn on the x axis.


The supplied function will be called once for each level of each factor in the design and the plot will show these summary values. The levels of a particular factor are shown along a vertical line, and the overall value of fun() for the response is drawn as a horizontal line.

This is a new R implementation which will not be completely compatible to the earlier S implementations. This is not a bug but might still change.


A big effort was taken to make this closely compatible to the S version. However, col (and fg) specification has different effects.


Roberto Frisullo and Martin Maechler


Chambers, J. M. and Hastie, T. J. eds (1992) Statistical Models in S. Chapman & Hall, London, the white book, pp. 546–7 (and 163–4).

Freeny, A. E. and Landwehr, J. M. (1990) Displays for data from large designed experiments; Computer Science and Statistics: Proc. 22nd Symp. Interface, 117–126, Springer Verlag.

See Also

interaction.plot for a “standard graphic” of designed experiments.

Examples automatic for data frame with one numeric var.

Form <- breaks ~ wool + tension
summary(fm1 <- aov(Form, data = warpbreaks))       Form, data = warpbreaks, col = 2)# same as above

## More than one y :
utils::str(esoph) ## two plots; if interactive you are "ask"ed

## or rather, compare mean and median:
op <- par(mfcol = 1:2) ~ ., data = esoph, ylim = c(0, 0.8)) ~ ., data = esoph, ylim = c(0, 0.8),
            fun = median)

[Package graphics version 2.5.0 Index]