How many standard deviations a value is from the mean.
To find the Z-score of a value:
· first subtract the mean,
· then divide by the standard deviation
Example: the class tried throwing a heavy weight, the average (mean) distance was 1.4, and standard deviation of 0.15.
Sam threw it 1.7, and subtracting 1.4 from 1.7 leaves 0.3, dividing that by 0.15 gives 2, so Sam's Z-score is 2.
A throw of 1.85 would have a Z-score of 3.