pj = number of people in the sample who answered question j correctly
qj = number of people in the sample who didn’t answer question j correctly
σ2 = variance of the total scores of all the people taking the test = VARP(R1) where R1 = array containing the total scores of all the people taking the test.
Values range from 0 to 1. A high value indicates reliability, while too high a value (in excess of .90) indicates a homogeneous test.