The Standard Deviation of a set of data describes the amount of variation in the data set by measuring, and essentially averaging, how much each value in the data set varies from the calculated mean.
The formula for standard deviation depends on whether you are analyzing population data, in which case it is called σ or estimating the population standard deviation from sample data, which is called s:
This means that the “typical” depth sample varies from the average depth by 3.55 feet.
