Plus situations where it can be useful
How to Calculate Mean and Standard Deviation in Excel
In statistics, standard deviation is a measure of how spread out a set of data is from the mean. Simply put, it tells you how "spread out" a collection of data points is.
This is useful for things like understanding how varied the grades of students in a classroom are, or measuring how much the temperature of something fluctuates over time. In particular, it can help you understand the differences between two data sets that might share the same average.
Such as two classes of students who get the same average grade, but with a few students who do much worse (or much better) in one class than in the other.
