Calculate the polychoric correlation coefficient between two polytomous (categorical ordinal) variables.
Polychoric correlation estimates the correlation between two theorized normally distributed
continuous latent variables from two observed ordinal variables.
Arguments
- x
A polytomous vector (categorical ordinal variable)
- y
A polytomous vector (categorical ordinal variable)
Value
The polychoric correlation coefficient between x and y
Details
This function handles missing values (coded as -1 or NA) using pairwise deletion.
The estimation uses maximum likelihood approach with Brent's method for optimization.
Examples
# Example with simulated data
set.seed(123)
x <- sample(1:5, 100, replace = TRUE)
y <- sample(1:4, 100, replace = TRUE)
polychoric(x, y)
#> [1] -0.1981319
