comorbidity {psych}R Documentation

Convert base rates of two diagnoses and their comorbidity into phi, Yule, and tetrachorics

Description

In medicine and clinical psychology, diagnoses tend to be categorical (someone is depressed or not, someone has an anxiety disorder or not). Cooccurrence of both of these symptoms is called comorbidity. Diagnostic categories vary in their degree of comorbidity with other diagnostic categories. From the point of view of correlation, comorbidity is just a name applied to one cell in a four fold table. It is thus possible to analyze comorbidity rates by considering the probability of the separate diagnoses and the probability of the joint diagnosis. This gives the two by two table needed for a phi, Yule, or tetrachoric correlation.

Usage

comorbidity(d1, d2, com, labels = NULL)

Arguments

d1 Proportion of diagnostic category 1
d2 Proportion of diganostic category 2
com Proportion of comorbidity (diagnostic category 1 and 2)
labels Names of categories 1 and 2

Value

twobytwo The two by two table implied by the input
phi Phi coefficient of the two by two table
Yule Yule coefficient of the two by two table
tetra Tetrachoric coefficient of the two by two table

Note

Requires the polycor package

Author(s)

William Revelle

See Also

phi, Yule

Examples

if(require(polycor)) {comorbidity(.2,.15,.1,c("Anxiety","Depression")) }

[Package psych version 1.0-67 Index]