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 |
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:
Values near 1: Strong positive discrimination
Values near 0: No discrimination
Negative values: Potential item problems
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)