Expands a wide-form matrix of item responses to a long-form data frame of sub-item responses
Usage
dendrify(mat, cmx)
Arguments
mat
An integer matrix of IRT responses (columns represent
items, rows represent respondents)
cmx
A mapping matrix with as many rows as there are response options for the items.
Value
A data frame with one row per sub-item response
References
De Boeck, P. and Partchev, I. (2012).
IRTrees: Tree-Based Item Response Models of the GLMM Family,
Journal of Statistical Software -- Code Snippets, 48(1), 1--28.
https://www.jstatsoft.org/v48/c01/.