Akademik

A statistical measurement of central tendency or average of a set of values, usually assumed to be the arithmetic m. unless otherwise specified. [M.E., mene fr. O.Fr., fr. L. medianus, in the middle]

- arithmetic m. the m. calculated by adding a set of values and then dividing the sum by the number of values.

- geometric m. the m. calculated as the antilogarithm of the arithmetic m. of the logarithms of the individual values; it can also be calculated as the nth root of the product of n values.

- harmonic m. the m. calculated as the number of values being averaged, divided by the sum of their reciprocals.

- regression of the m. if, for a symmetrical population with a single mode, a measurement, selected because it is extreme, is repeated, on average the second reading will be closer to the m. than the first.

- standard error of the m. (SEM) a statistical index of the probability that a given sample m. is representative of the m. of the population from which the sample was drawn.

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 value of 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.