ABSTRACT
The table below gives the cumulative probability values for normal Z standard deviation scores. The cumulative probability attached to each Z score is equivalent to the area underneath the normal curve from minus infinity to each Z score. The critical values of Z for a significant level of p = 0.05 (two-tailed) are −1.96 and +1.96. The critical values of Z for a significant level of p = 0.01 (two-tailed) are −2.576 and +2.576
