The data could therefore be coded as follows:

Condition Outcome 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Of the 10 subjects in Condition 1 (Experimental Condition), 8 have scores of 1 (success) and 2 have scores of 0 (failure). Of the 10 subjects in Condition 2 (Control Condition) 1 has a score of 1 (success) and 9 have scores of 0 (failure). Pearson's correlation between these two variables is 0.7035. Therefore, φ = 0.7035. Since the proportion of variance explained in correlation is the correlation coefficient squared, the proportion of variance explained is: φ² = 0.7035² = 0.495. Therefore, about 50% of the variance in outcome is explained by the treatment effect.