What are outliers in a statistical sample?

Outliers in a statistical sample are defined as items that lie significantly above or below the mean, indicating they are unusual observations within the data set. These values deviate from the overall trend or pattern of the data and can skew results or interpretations if not appropriately addressed. In a normal distribution, outliers are particularly notable, as normal distributions assume that data points are symmetrically distributed around the mean, making any substantial deviations clear indicators of outliers.

By identifying these outliers, researchers can investigate whether they result from variability in the data, measurement errors, or other factors, and determine how they should impact further analysis or conclusions. Properly recognizing and managing outliers is vital for ensuring accurate statistical interpretations and the integrity of research findings.