tetrachoric: Tetrachoric Correlation

In exametrika: Test Theory Analysis and Biclustering

Tetrachoric Correlation

Description

Tetrachoric Correlation is superior to the phi coefficient as a measure of the relation of an item pair. See Divgi, 1979; Olsson, 1979;Harris, 1988.

Usage

tetrachoric(x, y)

Arguments

x	binary vector x
y	binary vector y

Value

Returns a single numeric value of class "exametrika" representing the tetrachoric correlation coefficient between the two binary variables. The value ranges from -1 to 1, where:

• 1 indicates perfect positive correlation

• -1 indicates perfect negative correlation

• 0 indicates no correlation

References

Divgi, D. R. (1979). Calculation of the tetrachoric correlation coefficient. Psychometrika, 44, 169–172.

Olsson, U. (1979). Maximum likelihood estimation of the polychoric correlation coefficient. Psychometrika,44, 443–460.

Harris, B. (1988). Tetrachoric correlation coefficient. In L. Kotz, & N. L. Johnson (Eds.), Encyclopedia of statistical sciences (Vol. 9, pp. 223–225). Wiley.

exametrika documentation built on Aug. 21, 2025, 5:27 p.m.