Mean, Median, and Mode
The mean, which was described in the previous section of this book, is the balance point in a distribution. It is the most frequently used average.1
An alternative average is the median. It is the value in a distribution that has 50% of the cases above it and 50% of the cases below it. Thus, it is defined as the middle point in a distribution. In Example 1 below, there are 11 scores. The middle score, with 50% on each side, is 81, which is the median. Thus, 81 is the value of the median for the set of scores. Note that there are five scores above 81 and five scores below 81.2
Example 1: Scores (arranged in order from low to high):
61, 61, 72, 77, 80, 81, 82, 85, 89, 90, 92
In Example 2 below, there are 6 scores. Because there is an even number of scores, the median is halfway between the two middle scores. To find the halfway point, sum the two middle scores (7 + 10 = 17) and divide by 2 (17/2 = 8.5). Thus, 8.5 is the value of the median of the set for scores in Example 2.