A statistical term meaning the value obtained when you add up the total of a set of observations and divide the result by the number of observations. It can give a false impression if there are a few outliers – individual results well beyond the range of the remainder.
(arithmetic mean) n. the average of a group of observations calculated by adding their values and dividing by the number in the group. When one or more observations are substantially different from the rest, which can influence the arithmetic mean unduly, it is preferable to use the geometric mean (a similar calculation based on the logarithmic values of the observations) or – more commonly – the median (the middle observation of the series arranged in ascending order). A further method of obtaining an average or summary value for a group is to identify the mode – the observation (or group of observations when these occur as a continuous quantitative *variable) that occurs most often in the series.
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