If a dataset contains two outliers far from the rest, what is their typical impact on the mean and the median?

If a dataset contains two outliers far from the rest, what is their typical impact on the mean and the median?

• A. They can skew the mean; the median is less affected.
• B. They always reduce the mean and increase the median.
• C. They do not affect any measure.
• D. They only affect the mode.

Answer: (D)

Extreme values pull the average toward themselves because the mean uses every value in the dataset. The median, by contrast, depends on the order of the values and sits at the middle position, so it is much less affected by how large or small the extreme values are. With two far-out outliers, the mean will shift toward those outliers, while the median stays about where it was in the rest of the data. So the typical impact is that outliers skew the mean more than the median. The mode isn’t primarily affected by extremes in most cases, which is why it isn’t the focus here.

Extreme values pull the average toward themselves because the mean uses every value in the dataset. The median, by contrast, depends on the order of the values and sits at the middle position, so it is much less affected by how large or small the extreme values are.

With two far-out outliers, the mean will shift toward those outliers, while the median stays about where it was in the rest of the data. So the typical impact is that outliers skew the mean more than the median. The mode isn’t primarily affected by extremes in most cases, which is why it isn’t the focus here.