Plot Item Response Functions for a Summated Rating Scale

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Description

This function plots the rest scale (i.e., the scale excluding item j) against the variable Xj.

Usage

1

Arguments

X

A matrix of numeric variables that are being subjected to an item analysis in a summated rating scale.

jitter

The factor by which the y-values will be jittered

...

Other arguments to be passed to xyplot

Details

This function plots the rest scale (i.e., the scale excluding item j) against the variable Xj. This amounts to a visual investigation of the monotone homogeneity assumption in the summated rating model

Value

A plot of each variable against its rest score (i.e., the item response function) and a plot of all item response functions in a single pane.

Author(s)

Dave Armstrong