Final answer:
The mean alone does not provide information about the spread or distribution of scores, so additional measures like the standard deviation or range are needed.
Step-by-step explanation:
Knowing only the mean doesn't tell you everything about how scores relate to one another because the mean is just the average of all the scores in a set of data. It does not provide information about the spread or distribution of the scores. To fully understand the relationship between scores, you need additional measures like the standard deviation or the range. For example, two sets of data can have the same mean but very different distributions, with one having scores clustered closely around the mean and the other having scores spread out.