<P> The median can be used as a measure of location when a distribution is skewed, when end - values are not known, or when one requires reduced importance to be attached to outliers, e.g., because they may be measurement errors . </P> <P> A median is only defined on ordered one - dimensional data, and is independent of any distance metric . A geometric median, on the other hand, is defined in any number of dimensions . </P> <P> The median is one of a number of ways of summarising the typical values associated with members of a statistical population; thus, it is a possible location parameter . The median is the 2nd quartile, 5th decile, and 50th percentile . Since the median is the same as the second quartile, its calculation is illustrated in the article on quartiles . A median can be worked out for ranked but not numerical classes (e.g. working out a median grade when students are graded from A to F), although the result might be halfway between grades if there is an even number of cases . </P> <P> When the median is used as a location parameter in descriptive statistics, there are several choices for a measure of variability: the range, the interquartile range, the mean absolute deviation, and the median absolute deviation . </P>

Is the 50th percentile the mean or median