# interaction2wt

From HH v1.5
by Richard Heiberger

##### Plot all main effects and twoway interactions in a multifactor design

The main diagonal
displays boxplots for the main effects of each factor. The
off-diagonals show the interaction plots for each pair of factors.
The `i,j`

panel shows the same factors as the `j,i`

but with
the trace- and x-factor roles interchanged.

##### Usage

```
interaction2wt(x, ...)
## S3 method for class 'formula':
interaction2wt(x, data = sys.parent(), responselab, ...)
## S3 method for class 'default':
interaction2wt(x,
response.var,
responselab = deparse(substitute(y)),
relation = list(x = "free", y = "same"),
x.relation = relation$x,
y.relation = relation$y,
digits = 3,
x.between = c(1, rep(0, ncol(x) - 1)),
y.between = NULL,
cex = 0.75,
panel.input = panel.interaction2wt,
strip.input = strip.interaction2wt,
par.strip.text.input = list(cex = 0.7),
scales.additional,
main.in =
paste(responselab,
": main effects and 2-way interactions",
sep = ""),
xlab.in = TRUE,
xlab = list(labels = ""),
ylab = list(labels = ""),
...,
main.cex)
```

##### Arguments

- x
- The object on which method dispatch is carried out.
For the
`"formula"`

method, a formula describing the response variable and factors. The formula is generally of the form`y ~ g1 + g2 + ...`

. There may be one - data
- For the
`formula`

method, a data frame containing values for any variables in the formula. In the R version, if not found in`data`

, or if`data`

is unspecified, the variables are looked for in the env - responselab
- Character name of response variable, defaults to
the name of the response variable in the
`formula`

. - ...
- additional arguments, primarily trellis arguments.
- response.var
- For the
`"default"`

method, the response variable. This is usually constructed by`formula`

method from the input data and the input formula. - relation
`trellis`

argument.- x.relation
`x`

value of`relation`

argument.- y.relation
`y`

value of`relation`

argument.- digits
- doesn't do anything at the moment
- x.between
`x`

value of`relation`

argument.- y.between
`y`

value of`relation`

argument.- cex
- S-Plus: changes the size of the median dot in the boxplots. R: doesn't do anything.
- panel.input
- panel function. Default is
`panel.interaction2wt`

. - strip.input
- strip function. Default is
`strip.interaction2wt`

. - par.strip.text.input
`par.strip.text`

argument.- scales.additional
- additional arguments to
`scales`

argument. - main.in
- Text of main title.
- xlab.in
- S-Plus: FALSE suppresses x labels in trellis. R: no effect.
- xlab
- No effect.
- ylab
- No effect.
- main.cex
`cex`

for main title.

##### Value

`"trellis"`

object containing the plot.

##### References

Heiberger, Richard M. and Holland, Burt (2004b).
*Statistical Analysis and Data Display: An Intermediate Course
with Examples in S-Plus, R, and SAS*.
Springer Texts in Statistics. Springer.
ISBN 0-387-40270-5.

##### See Also

##### Examples

```
anova(aov(len ~ supp*dose, data=ToothGrowth))
interaction2wt(len ~ supp + dose, data=ToothGrowth)
bwplot(len ~ supp | dose, data=ToothGrowth, layout=c(3,1))
```

*Documentation reproduced from package HH, version 1.5, License: GPL version 2 or newer*

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