rirf: Item Functions

In Rwinsteps: Running Winsteps in R

Description

These functions return the item response, item inforamtion, item error, test response, the test information, and the test error functions for a set of Rasch item location, i.e., difficulty parameters.

Usage

rirf(x, theta = seq(-4, 4, length = 100))

riif(x, theta = seq(-4, 4, length = 100))

rief(x, theta = seq(-4, 4, length = 100))

rtrf(x, theta = seq(-4, 4, length = 100))

rtif(x, theta = seq(-4, 4, length = 100))

rtef(x, theta = seq(-4, 4, length = 100))

Arguments

x	numeric item location or a vector of item locations, or an ifile
theta	optional vector of theta values over which the functions will be evaluated

Details

rirf evaluates the Rasch model for each item location over theta, returning the probabilities correct. The remaining functions all incorporate these probablities to return the information (riif and standard errors (rief) for each item across theta, or aggregates of these values across a set of items (rtrf for the test response function, rtiffor the test information function, and rtef for the test error function).

Value

A list is returned containing theta and the corresponding item function.

Author(s)

Anthony Albano [e-mail]

See Also

plot.ifile

Examples

rirf(-2)
rtrf(-2:2)

Rwinsteps documentation built on May 2, 2019, 1:08 p.m.