Which measure of central tendency is most affected by extreme values?

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

Answer: (C)

The idea here is how outliers influence where we think the center of a data set lies. The mean, or the arithmetic average, uses every value in the data set. Because of that, one unusually large or small value can shift the total enough to move the average toward that extreme. For example, with numbers like 1, 2, 2, 2, 100, the average is 21.4, a big jump from the central cluster, while the middle value (the median) remains around 2. The mode would stay at 2 as well if that value is the most frequent.

The median, being the middle value after ordering, is less sensitive to outliers because it depends on position rather than the magnitude of the numbers. The mode is about which value occurs most often, so a single extreme value usually doesn’t change it unless it creates a new most-frequent value. Range, on the other hand, measures spread—the distance between the smallest and largest values—not a central value, so it isn’t a measure of center at all.

So the mean is the measure most affected by extreme values because it incorporates every data point, including outliers, into the calculation.