Which measure of central tendency is least affected by outliers?

• A. Mean
• B. Median
• C. Mode
• D. Range

Answer: (B)

Outliers distort numbers, so the measure that stays most stable is the median. Since the median is the middle value when the data are ordered, it depends on position rather than how extreme the values are, so a single outlier barely moves it. The mean, on the other hand, uses every data point, so an extreme value pulls it toward itself. The range is about spread, not center, and can swing a lot with an outlier. The mode is about the most frequent value and can change if an outlier affects which value occurs most often, but that isn’t a reliable shield against outliers. So the median is the least affected by outliers.