phi.demo {psych}R Documentation

Create demo data for psychometrics

Description

A not very interesting demo of what happens if bivariate continuous data are dichotomized. Bascially a demo of r, phi, and polychor.

Usage

phi.demo(n=1000,r=.6, cuts=c(-2,-1,0,1,2))

Arguments

n number of cases to simulate
r correlation between latent and observed
cuts form dichotomized variables at the value of cuts

Details

A demonstration of the problem of different base rates on the phi correlation, and how these are partially solved by using the polychoric correlation. Not one of my more interesting demonstrations. See http://personality-project.org/r/simulating-personality.html and http://personality-project.org/r/r.datageneration.html for better demonstrations of data generation.

Value

a matrix of correlations and a graphic plot)

Author(s)

William Revelle

References

http://personality-project.org/r/simulating-personality.html and http://personality-project.org/r/r.datageneration.html for better demonstrations of data generation.

See Also

VSS.simulate,item.sim

Examples

round(phi.demo() ,2)  #compare the phi (lower off diagonal and polychoric correlations (upper off diagonal)

[Package psych version 1.0-67 Index]