In
statistics, the
standard deviation (
SD, also represented by the Greek letter sigma
s or
s) is a measure that is used to quantify the amount of variation or
dispersion of a set of data values. A standard deviation close to 0 indicates that the data points tend to be very close to the
mean (also called the expected value) of the set, while a high standard deviation indicates that the data points are spread out over a wider range of values.