What is the mean of a data set with its most extreme 5% of values removed called?

• A. Trimmed mean
• B. Mean
• C. Median
• D. Mode

Answer: (A)

Removing the most extreme values before averaging gives you a trimmed mean. A 5% trimmed mean means you discard the lowest 5% and the highest 5% of observations and then compute the average of what remains. This approach reduces the influence of outliers or extreme skew, providing a central tendency measure that is more robust than the ordinary mean. If data are fairly symmetric and free of outliers, the trimmed mean will be similar to the regular mean; with outliers, it shifts closer to the median because those extreme values no longer pull the average as strongly. The ordinary mean uses all data, the median is the middle value, and the mode is the most frequent value, but the trimmed mean sits between mean and median in its behavior depending on the distribution.