**Average**, **mean**, **median**, **norm**, **par** denote something and usually a number, a quantity, or a condition that represents a middle point between extremes. Of these words average, mean, median, and par are also used as adjectives.

**Average** is an arithmetical term applied to a quotient obtained by dividing a total by the number of items entering into this total so that the quotient represents the value each item would have if all were alike; thus, the *average *of 10, 12, 14, 16, 18, 20 is 15 (that is, 90 + 6).

Such averages are computed to give one a fair estimate of a group or a series in which there are inequalities. When (as in sports) the total represents the number of chances taken or of pportunities offered or provided, the *average *is obtained by dividing the number of successes or successful performances by this total.

Such an average may be expressed as a percentage or a permillage and gives a fair estimate of a player's performance and a basis for comparison with others; thus, a baseball first baseman who handles a total of 1114 chances and makes 6 errors has a fielding *average *of .9946 (that is,' 1108 -^ 1114); a baseball batter who is credited with 605 appearances at bat and has made 201 hits has a batting *average *of .332 (that is, 201 -r- 605).

A similar method is used in estimating probabilities (as the chances of death for a person between given ages and the length of the period between recurrences of an unpredictable phenomenon); thus, the *average *of mortality for persons of a given age is computed from statistics of deaths at that age and of the population group consisting of persons of that age.

*Average *also may be applied to a concept of what is the typical or ordinary person or thing of its kind (see also *average, *under MEDIUM).

**Mean** originally and still in certain idioms named a condition, quality, intensity, or rate that is midway between two extremes <observe a happy *mean *between abjectness and arrogance or between effusiveness and reserve).

In its mathematical use *mean *is more general than *average *(for which another name is *arithmetical mean): *it covers also the *geometric mean, *that is, the square root of the product of two numbers or quantities (or the *nth *root of the product of *n *quantities); thus, 10 is the *arithmetical **mean *or *average *of 4 , 16; while 8 is the *geometric **mean *of 4 , 16. Median refers to a midway point in position; in statistics it names the figure or quantity which represents the point at which there are as many instances below as there are above it; thus, the *average *of a group of 5 workers earning respectively 6, 8, 10, 16, and 20 dollars a day is 12 dollars a day, whereas the *median *for the same group is 10 dollars, because one half of them earn less than 10 dollars a day and one half more.

**Norm **suggests a rule for guidance or a definite pattern to be followed; it also denotes especially in such fields as psychology and sociology, an average, whether mathematically computed or estimated, of performance or achievement of a group, class, or category that can be set up as a standard for or a minimum of accomplishment by a similar larger group, class, or category; thus, a course of study for a particular school grade is based upon a *norm *determined by the performance of children of the age, experience, and background commonly found in that grade.

**Par **usually refers to an average for an individual that is like the *norm *for a group. It often refers to an individual person's average in health, accomplishment, or performance.

In British use *par *may be employed in reference to an average in amount.