Which is a drawback of using the range?

• A. It uses only the two most extreme scores
• B. It uses all data points in calculation
• C. It is highly precise
• D. It is unaffected by outliers

Answer: (A)

Range is a simple measure of spread that uses only the smallest and largest values to calculate the distance between them. Its main feature is that it relies on those two extreme scores, ignoring all the other data points. Because of this, it can give a misleading picture of the data: if there are a couple of extreme values, the range can be large even when most scores are close together; if the extremes are not representative, the range might suggest more or less variability than actually exists for most observations. This lack of information about the rest of the data makes the range a crude, not very precise, measure and it’s sensitive to outliers. So the drawback is that it uses only the two most extreme scores, which is why it’s not a robust summary of spread.