Fn key. Not to be confused with Function key. The Fn key, short form for function, is a modifier key on many keyboards, especially on laptops, used in a compact layout to combine keys which are usually kept separate. It is typically found on laptops due to their keyboard size restrictions.
For a finite set of numbers, the standard deviation is found by taking the square root of the average of the squared deviations of the values from their average value. For example, the marks of a class of eight students (that is, a population) are the following eight values:
Statistics of the distribution of deviations are used as measures of statistical dispersion. 1  Standard deviation is the frequently used measure of dispersion: it uses squared deviations, and has desirable properties, but is not robust. 2  Average absolute deviation, is the sum of absolute values of the deviations divided by the number of observations. Median absolute deviation is a robust statistic which uses the median, not the mean, of absolute deviations.