ABSTRACT
The median is the middle score in a distribution. Being in the middle, it always has 50% of the scores above it and 50% of the scores below it. The median is preferable to the mean when a distribution is highly skewed. It also is used to describe the average when the data are ordinal but do not have equal intervals among them. When the median is reported as the average, it is customary to report the range or interquartile range as a measure of variability. Variability refers to the amount by which participants vary or differ from each other. Measurement theory indicates that the more extreme the score, the more unreliable or likely to reflect errors it is. To get around this problem, researchers often use a modified version of the range, which is called the interquartile range. The formal definition of the interquartile range is the range of the middle 50% of the participants.
