is about dichotomous variable tetrachoric correlation coefficient 2 Orlaith Burke Alejandra Gonzalez-Beltran Philippe Rocca-Serra a tetrachoric correlation coefficient is a polychoric correlation coefficient for 2 dichotomous variables used as proxy for correlation between 2 continuous latent variables. adapted from: http://www.rasch.org/rmt/rmt193c.htm and http://en.wikipedia.org/wiki/Polychoric_correlation polychoric correlation coefficient ready for release