The Z score itself is a statistical measurement of the number of standard deviations from the mean of a normal distribution. In other words, Z tables help compare data points within a group and show what percentage they are above or below the group average. Z-tables help graphically display the percentage of values above or below a z-score in a group of data or data set. Definition: A Z-Score table or chart, often called a standard normal table in statistics, is a math chart used to calculate the area under a normal bell curve for a binomial normal distribution.
