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)
# S3 method for default
TetrachoricCorrelationMatrix(U, na = NULL, Z = NULL, w = NULL)
# S3 method for binary
TetrachoricCorrelationMatrix(U, na = NULL, Z = NULL, w = NULL)
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.
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.