The standard deviation is a measure of how spread out numbers are.
Its symbol is σ (the Greekletter sigma)
The formula is easy: it is the square root of the variance.
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- A low standard deviation indicates that the data points tend to be close to the mean (also called the expected value) of the set.
- A high standard deviation indicates that the data points are spread out over a wider range of values.
The standard deviation is commonly used to measure confidence in statistical conclusions.