A set of data has a high-value outlier. How do you expect the standard deviation to change when the outlier is removed? Would the result be different if the data had a low-value outlier instead? Explain.

Correct Answer:

The standard deviation will decrease when the outlier is removed. Standard deviation represents the spread of data from the mean. Both highvalue and lowvalue outliers increase the spread of a data set. Therefore, removing either a highvalue or a lowvalue outlier decreases the spread from the mean, which results in a lower standard deviation.