What the standard deviation really tells you is that some set of users were + or - the test average (or arithmeticmean).
标准偏差真正能够告诉您的是,某些用户是高于还是低于平均测试水平(或者算术含义)。
2
In fact, there are some very old books that show this as the average, the sum divided by two arithmeticmean, but the modern practice is to use the geometric mean.
Under the certain conditions, the average RCS of targets with complex shape are generally subject to the arithmetic sum of the mean RCS by local reflection area.