In a dataset of hospital lengths of stay, which measure is less influenced by extreme values?

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

Answer: (B)

Extreme values can distort some summaries of a dataset. The mean uses every data point, so a very high or very low hospital stay can pull the average toward that outlier. The median, however, is the middle value when the data are ordered, so it stays put when a few extreme values appear, as long as they don’t change which value sits in the middle. For example, with lengths like 2, 3, 3, 4, 100, the mean jumps to 22.4 while the median remains 3. The mode depends on the most frequent value and can be unstable if outliers affect frequencies; the range directly reflects the smallest and largest values, so it is highly sensitive to extremes. Because the median resists the influence of outliers, it is the measure that is less influenced by extreme values.