CDM (version 2.7-7)

skill.cor: Tetrachoric Correlations between Attributes

Description

This function takes the results of din or gdina and computes tetrachoric correlations between attributes (see e.g. Templin & Henson, 2006).

Usage

skill.cor(object)

Arguments

object

Object of class din or gdina

Value

• A list with following entries:
• conttable.skills
  Bivariate contingency table of all skill pairs
• cor.skills
  Tetrachoric correlation matrix for skill distribution

References

Templin, J., & Henson, R. (2006). Measurement of psychological disorders using cognitive diagnosis models. Psychological Methods, 11, 287-305.

Examples

# estimate model
d4 <- din(sim.dino, q.matr = sim.qmatrix)
# compute tetrachoric correlations
skill.cor(d4)
## estimated tetrachoric correlations
##   $cor.skills
##             V1        V2        V3
##   V1 1.0000000 0.2567718 0.2552958
##   V2 0.2567718 1.0000000 0.9842188
##   V3 0.2552958 0.9842188 1.0000000