Coefficient Phi

The Phi coefficient is a measure of correlation between two categorical variables in a 2x2 table.

Its value can range from -1 to 1 where values closer to 0 indicate no relation between factors and values closer to either -1 or 1 indicate a perfect relation between the two factors.

For more details concerning this statistic, see Castellan and Siegel (1988, p. 232) or Sheskin (1997).