TetrachoricCorrelationMatrix {exametrika}R Documentation

Tetrachoric Correlation Matrix

Description

Calculates the matrix of tetrachoric correlations between all pairs of items. Tetrachoric Correlation is superior to the phi coefficient as a measure of the relation of an item pair. This function is applicable only to binary response data.

Usage

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

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

## S3 method for class 'binary'
TetrachoricCorrelationMatrix(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 tetrachoric correlations with exametrika class. Each element (i,j) represents the tetrachoric correlation 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
TetrachoricCorrelationMatrix(J15S500)


[Package exametrika version 1.5.1 Index]