The median (Md) is another measure of central tendency. The median can be used with continuous and ordinal data; it cannot be used with nominal data, however, because it requires that the variable under examination be rank orderable, which nominal variables are not.
Median: The score that cuts a distribution in half such that 50% of the scores are above that value and 50% are below it.
The median is the value that splits a data set exactly in half such that 50% of the data points are below it and 50% are above it. For this reason, the median is also sometimes called the 50th percentile. The median is a positional measure, which means that it is not so much calculated as it is located. Finding the median is a three-step process. First, the categories or scores need to be rank ordered. Second, the median position (MP) can be computed using the formula
where
N = total sample size
The median position tells you where the median is located within the ranked data set. The third step is to use the median position to identify the median. When N is odd, the median will be a value in the data set. When N is even, the median will have to be computed by averaging two values.