R: Summarizing and Visualizing Item Response Data

summary.itemresp {psychotools} | R Documentation

## Summarizing and Visualizing Item Response Data

### Description

Summarizing and visualizing `"itemresp"` data objects.

### Usage

      ## S3 method for class 'itemresp'
    summary(object, items = NULL, abbreviate = FALSE,
        mscale = TRUE, simplify = TRUE, sep = " ", ...)
      ## S3 method for class 'itemresp'
    plot(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), ...)

### Arguments

`object, x` | an object of class `"itemresp"`.
`items` | character or integer for subsetting the items to be summarized/visualized. By default, all items are used.
`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.
`mscale` | logical. Should mscale values be used for printing/plotting? If `FALSE`, integers 0, 1, ... are used.
`simplify` | logical. Should the summary table be collapsed into a matrix or returned as a list?
`sep` | character. A character for separating item labels from their corresponding scale labels (if any).
`xlab, ylab, off, axes, ...` | arguments passed to `spineplot`.
`names` | logical or character. If `TRUE`, the names of the items are displayed on the x-axis. If `FALSE`, numbers of items are shown. Alternatively a character vector of the same length as the number of items can be supplied.
`srt, adj` | numeric. Angle (`srt`) and adjustment (`adj`) in case names (rather than numbers) are used as x-axis labels. These are passed to `text`.

### Details

The `plot` method essentially just calls `summary` (passing on most further arguments) and then visualizes the result as a `spineplot`.

### See Also

`itemresp`, `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)

[Package psychotools version 0.4-2 Index]