Standard Deviation Pros and Cons

Sometimes we can’t use the mean because we have too much skew or extreme scores. In those situations, the mean is meaningless.

In the above example, we have data with a mean of 4 and an extreme data point of 13. However, we can clearly see that the typical score is around 2 or 3, therefore the mean is showing us the incorrect result.

In this scenario, the standard deviation will also show us an incorrect result.

As a general rule: when there is a large skew in the data, we can’t use mean or standard deviation.

For this reason, we’re going to have to use the backup option of the interquartile range, which will be covered in the next activity.