This function computes the omega coefficient of the tau-congeneric measurement model (McDonald, 1999) for a given data set.
Arguments
- x
This should be a data matrix or a Covariance/Phi/Tetrachoric matrix.
- na
This parameter identifies the numbers or characters that should be treated as missing values when 'x' is a data matrix.
- Z
This parameter represents a missing indicator matrix. It is only needed if 'x' is a data matrix.
- w
This parameter is an item weight vector. It is only required if 'x' is a data matrix.
Value
For a correlation/covariance matrix input, returns a single numeric value representing the omega coefficient. For binary data, returns a list with three components:
- OmegaCov
Omega coefficient calculated from covariance matrix
- OmegaPhi
Omega coefficient calculated from phi coefficient matrix
- OmegaTetrachoric
Omega coefficient calculated from tetrachoric correlation matrix
For ordinal data, returns a list with OmegaCov (from the covariance
matrix of the category scores) and OmegaPolychoric (from the
polychoric correlation matrix). Rated and nominal data are not supported.