Algorithm 1. Formula for calculating sample size

Analysis: A priori: Compute the required sample size Input:  Tail(s)     = Two    Effect size |ρ| = 0.18     α err probability  =  0.05    Power (1 − β err probability)  =  0.95 Output:  Noncentrality parameter δ =   3.6183698 Critical t =     1.9660811 Df  =  389 Total sample size  =  39 Actual power  =  0.9504731