The Standard Deviation is the square root of the arithmetic mean of the squares of the deviations from the arithmetic mean.
In other words:
| 1. | Average the numbers in a distribution |
| 2. | Subtract the number from the average |
| 3. | Square the differences |
| 4. | Average all the results |
| 5. | The standard deviation is the average (mean) of numbers calculated in step 4 |
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