Median
Definition
The middle value of a data set when arranged in ascending or descending order. It divides the distribution into two equal halves. For even n: Median = average of (n/2)th and (n/2 + 1)th values. It is NOT affected by extreme values.
Example
"Data: 12, 15, 18, 22, 30. Median (n=5, odd) = 3rd value = 18. If data were 12, 15, 18, 22: Median = (15+18)/2 = 16.5."