- mean
- 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.-the m. calculated as the*harmonic*m.*number*of values being averaged, divided by the sum of their reciprocals.-if, for a symmetrical*regression*of the m.*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.-(SEM) a statistical*standard**error*of the m.*index*of the*probability*that a given*sample*m. is representative of the m. of the*population*from which the*sample*was drawn.* * *

__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 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.* * *

(mēn) [Old Fr.*meien,*from L.*medianus*middle] 1. an average; a number that in some sense represents the central value of a set of numbers. 2. arithmetic m. 3. in probability and statistics, the expected value (mathematical expectation) of a random variable, the limiting value to which the sample mean converges as the sample size is increased indefinitely (if the limit exists).

*Medical dictionary.
2011.*