Definition: The median is a statistical measure of the average value in a distribution of scores. It is the score of the middle case in the distribution when the scores are arranged in order from lowest to highest. The middle case is the one that divides the distribution in half with an equal number of cases above and below it.
If three families have 2, 3, and 5 children respectively, the median for the distribution is 3 since it is the middle case. If the distribution has an equal number of cases, the median is calculated by taking the average of the two middle scores.