z-score

The z-score is the number of standard deviations a control result is from the expected mean. Use the following formula to calculate the z-score:

A z-score of 2.3 indicates the observed value is 2.3SD away from the expected mean. A data point with this z-score violates the 1_2s rule, but not the 1_3s rule. The z-score appears on the Single Test Point Data Entry dialog box.