ItemTotalCorr {exametrika}R Documentation

Item-Total Correlation

Description

Item-Total correlation (ITC) is a Pearson's correlation of an item with the Number-Right Score (NRS) or total score. This function is applicable only to binary response data.

The ITC is a measure of item discrimination, indicating how well an item distinguishes between high and low performing examinees.

Usage

ItemTotalCorr(U, na = NULL, Z = NULL, w = NULL, ...)

Arguments

U

U is a data matrix of the type matrix or data.frame.

na

na argument specifies the numbers or characters to be treated as missing values.

Z

Z is a missing indicator matrix of the type matrix or data.frame

w

w is item weight vector

...

Internal parameters for maintaining compatibility with the binary data processing system. Not intended for direct use.

Details

The correlation is calculated between:

Higher positive correlations indicate items that better discriminate between high and low ability examinees.

Value

A numeric vector of item-total correlations. Values typically 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.

Values below 0.2 might indicate problematic items that should be reviewed. Values above 0.3 are generally considered acceptable.

Examples

# using sample dataset
ItemTotalCorr(J15S500)


[Package exametrika version 1.1.0 Index]