When is a dataset said to have a mode?

A dataset is said to have a mode when at least one score appears more than once. The mode is defined as the value that occurs most frequently within a dataset. This means that if there is a number or set of numbers that repeats more than any other, then that number is considered the mode.

For instance, in the dataset {1, 2, 2, 3, 4}, the number 2 appears more times than any other value, making it the mode. A dataset can have one mode (unimodal), multiple modes (bimodal if there are two modes, or multimodal if there are multiple), or no mode at all if all numbers occur with the same frequency.

This definition highlights why the other choices do not qualify as the correct answer. Having all values different, for example, would imply no repeats and thus no mode. Similarly, a highest score that is significantly larger or an average that is greater than the median does not necessarily indicate the presence of a mode. The concept of a mode strictly revolves around frequency of occurrence, which is adequately captured in the correct answer.