The mean is one of several indices of central tendency that statisticians use to indicate the point on the scale of measures where the population is centered.

 

The mean is the average of the scores in the population. Numerically, it equals the sum of the scores divided by the number of scores. It is of interest that the mean is the one value which, if substituted for every score in a population, would yield the same sum as the original scores, and hence it would yield the same mean.

 

This illustration shows a population of 9 persons. It also shows the height of each person as well as the formula and calculations of the mean of the population. As is customary, we have used the Greek letter mu to represent the mean of a population.

 

The mode is one of several measures of central tendency that statisticians use to indicate the point (or points) on the scale of measures where the population is centered. It is the score in the population that occurs most frequently. Please notice that the mode is not the frequency of the most numerous score. It is the value of that score itself.

 

Also notice that if there are two (or more) different scores that occur with equal frequency and that frequency is higher than the frequency of any of the other scores, the population is described as multi-modal.

 

The median is one of several indices of central tendency that statisticians use to indicate the point on the scale of measures where the population is centered. The median of a population is the point that divides the distribution of scores in half. Numerically, half of the scores in a population will have values that are equal to or larger than the median and half will have values that are equal to or smaller than the median.

 

mean	The average where you add up all the # and then divide by the number of numbers	(∑x)/N
median	The middle value in the list of numbers	Sort numbers; If odd, pick the middle #, if even median is the average of the two middle numbers
mode	The mode is the value that occurs most often. If no number is repeated, then there is no mode for the list	The value repeated most often