You need three things to calculate a z-score: your score (X), the mean (bar-X) and the standard deviation (s).
A z-score tells you how far away you are from the mean in terms of standard deviations. If you are at the mean, you z-score is zero. If you are ½ standard deviation above the mean, your z-score is +.5. If you are one standard deviation below the mean, your z-score is -1.
A z-score tells you how many standard deviations your score is away from the mean. If z is positive, your score is above the mean. If z is negative, your score is below the mean. If your score is at the mean, z = 0.
Take your score (X) and subtract the mean from it. X with a bar over it is the symbol for the mean, and it’s pronounced bar-x (like the ranch on an old cowboy movie).
Divide the result of your subtraction by the standard deviation.
Takes it. It’s easier than mixing muffins, and there’s no preheating the oven.
