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\name{summary.itemresp}
\alias{summary.itemresp}
\alias{plot.itemresp}
\title{Summarizing and Visualizing Item Response Data}
\description{
Summarizing and visualizing \code{"itemresp"} data objects.
}
\usage{
\method{summary}{itemresp}(object, items = NULL, abbreviate = FALSE,
mscale = TRUE, simplify = TRUE, sep = " ", \dots)
\method{plot}{itemresp}(x, xlab = "", ylab = "", items = NULL,
abbreviate = FALSE, mscale = TRUE, sep = "\n", off = 2, axes = TRUE,
names = TRUE, srt = 45, adj = c(1.1, 1.1), \dots)
}
\arguments{
\item{object, x}{an object of class \code{"itemresp"}.}
\item{items}{character or integer for subsetting the items to be
summarized/visualized. By default, all items are used.}
\item{abbreviate}{logical or integer. Should scale labels be abbreviated?
Alternatively, an integer with the desired abbreviation length. The default
is some heuristic based on the length of the labels.}
\item{mscale}{logical. Should mscale values be used for printing/plotting?
If \code{FALSE}, integers 0, 1, \dots are used.}
\item{simplify}{logical. Should the summary table be collapsed into
a matrix or returned as a list?}
\item{sep}{character. A character for separating item labels from
their corresponding scale labels (if any).}
\item{xlab, ylab, off, axes, \dots}{arguments passed to \code{\link[graphics]{spineplot}}.}
\item{names}{logical or character. If \code{TRUE}, the names of
the items are displayed on the x-axis. If \code{FALSE}, numbers of
items are shown. Alternatively a character vector of the same
length as the number of items can be supplied.}
\item{srt, adj}{numeric. Angle (\code{srt}) and adjustment (\code{adj})
in case names (rather than numbers) are used as x-axis labels.
These are passed to \code{\link[graphics]{text}}.}
}
\details{
The \code{plot} method essentially just calls \code{summary} (passing on most further
arguments) and then visualizes the result as a \code{spineplot}.
}
\seealso{\code{\link{itemresp}}, \code{\link[graphics]{spineplot}}}
\examples{
## summary/visualization for verbal aggression data
data("VerbalAggression", package = "psychotools")
r <- itemresp(VerbalAggression$resp[, 1:6])
mscale(r) <- c("no", "perhaps", "yes")
summary(r)
plot(r)
## modify formatting of mscale
summary(r, abbreviate = 1)
summary(r, mscale = FALSE)
## illustration for varying mscale across items
## merge with additional random binary response
b <- itemresp(rep(c(-1, 1), length.out = length(r)),
mscale = c(-1, 1), labels = "Dummy")
rb <- merge(r[, 1:2], b)
head(rb, 2)
## summary has NAs for non-existent response categories
summary(rb)
summary(rb, mscale = FALSE)
plot(rb, srt = 25)
plot(rb, mscale = FALSE)
}
\keyword{classes}
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