plotINFO {eRm}

Plot Information For 'eRm' objects

Description

Calculates and plots the individual item-category information (type='category'), item information (type='item') or test/scale information (i.e., summed item information, type='scale' or 'test') ) as defined by Samejima (1969)

Usage

plotINFO(ermobject, type = "both", theta = seq(-6, 6, length.out = 1001L), 
legpos = "topright", ...)

Arguments

ermobject

An object of class 'eRm'.

type

A string denoting the type of information to be plotted. Currently supports "category", "item", "test", "scale" and "both" (which gives item and scale information; default).

theta

Supporting or sampling points on the latent trait.

legpos

Defines the positioning of the legend, as in plotICC.

...

Further arguments. xlab sets the label of the x axis. ylabI and ylabT control the labeling of the item or test information plot. mainI and mainT set the titles for item/test information plots.

Author(s)

Thomas Rusch

References

Samejima, F. (1969) Estimation of latent ability using a response pattern of graded scores. Psychometric Monographs, 17.

See Also

The function to calculate the item or test information, item_info and test_info.

Examples

res <- PCM(pcmdat)
plotINFO(res)