PhiCoefficient {exametrika}R Documentation

Phi-Coefficient

Description

The phi coefficient is the Pearson's product moment correlation coefficient between two binary items. This function is applicable only to binary response data. The coefficient ranges from -1 to 1, where 1 indicates perfect positive correlation, -1 indicates perfect negative correlation, and 0 indicates no correlation.

Usage

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

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

## S3 method for class 'binary'
PhiCoefficient(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 matrix of phi coefficients with exametrika class. Each element (i,j) represents the phi coefficient between items i and j. The matrix is symmetric with ones on the diagonal.

Note

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

Examples

# example code
# Calculate Phi-Coefficient using sample dataset J15S500
PhiCoefficient(J15S500)

[Package exametrika version 1.5.1 Index]