birtr {birtr} | R Documentation |

## The R Package for "The Basics of Item Response Theory Using R"

### Description

The birtr package provides nine important functions:
`iccplot()`

, `icccal()`

, `icc()`

, `iccfit()`

, `groupinv()`

,
`tcc()`

, `ability()`

, `tif()`

, and `rasch()`

.

### Details

The `iccplot()`

function plots an item characteristic curve under the
two-parameter logistic model.

The `icccal()`

function computes the logistic deviate L, the
exponent of negative L, the denominator, and the value of probability
of correct response for each of seven ability levels evenly spaced from
-3 to +3 under the one-, two-, or three-parameter logistic item
characteristic curve model.

The `icc()`

function plots an item characteristic curve under the one-,
two-, or three-parameter logistic model.

The `iccfit()`

function plots the item characteristic curve and the
simulated observed proportions of correct response from the one-, two-,
or three-parameter logistic model.

The `groupinv()`

function plots the item characteristic curve and
the two sets of simulated observed proportions of correct response from
two groups under the one-, two-, or three-parameter logistic model.

The `tcc()`

function plots a test characteristic curve from a set of
item parameters under the one-, two-, or three-parameter logistic model.

The `ability()`

function estimates the ability parameter and obtains
the standard error of the estimate given the item characteristic curve
model, the response vector, and the set of known item parameters under
the one-, two-, or three-parameter logistic model.

The `tif()`

function plots a test information function from a set of
item parameters under the one-, two-, or three-parameter logistic model.

The `rasch()`

function yields estimates of item difficulty parameters
and ability parameters under the one-parameter logistic Rasch model
by the Birnbaum paradigm.

### Author(s)

Seock-Ho Kim shkim@uga.edu

### References

Baker, F. B., & Kim, S.-H. (2017).
*The basics of item response theory using R.*
New York, NY: Springer.
ISBN-13: 978-3-319-54204-1

*birtr*version 1.0.0 Index]