ITBiserial {exametrika}R Documentation

Item-Total Biserial Correlation

Description

The Item-Total Biserial Correlation computes the biserial correlation between each item and the total score. This function is applicable only to binary response data.

This correlation provides a measure of item discrimination, indicating how well each item distinguishes between high and low performing examinees.

Usage

ITBiserial(U, na = NULL, Z = NULL, w = NULL)

## Default S3 method:
ITBiserial(U, na = NULL, Z = NULL, w = NULL)

## S3 method for class 'binary'
ITBiserial(U, na = NULL, Z = NULL, w = NULL)

Arguments

U

Either an object of class "exametrika" or raw data. When raw data is given, it is converted to the exametrika class with the dataFormat function.

na

Values to be treated as missing values.

Z

Missing indicator matrix of type matrix or data.frame. Values of 1 indicate observed responses, while 0 indicates missing data.

w

Item weight vector specifying the relative importance of each item.

Value

A numeric vector of item-total biserial correlations. Values range from -1 to 1, where:

Note

This function is implemented using a binary data compatibility wrapper and will raise an error if used with polytomous data.

The biserial correlation is generally preferred over the point-biserial correlation when the dichotomization is artificial (i.e., when the underlying trait is continuous).

Examples

# using sample dataset
ITBiserial(J15S500)

[Package exametrika version 1.5.1 Index]