Note: The formula for standard deviation involves (Greek, "Sigma") or "sum" notation. refers to the ith element in the data set, is the mean x-value.
- Find the difference between each value and the mean
- Square those differences
- Find the sum of all of the squares
- Divide that value by N (the number of data elements in the set)
- The Standard Deviation is the square root of the result
One way to understand the standard deviation is that it is kind of like the average distance from the mean in the data set.