An averaging method
designed to reduce the effects of statistical outliers. This is done by removing a small percentage of the largest and smallest values
among a set of numbers, before calculating the average
of those numbers. A trimmed mean is represented as a mean trimmed by X%, where X represents the total percentage of values removed from the upper and lower bounds. For example mean trimmed 20% has 10% of the largest numbers removed, and 10% of the smallest numbers removed.