The mode of a data set is the value that appears most frequently. Therefore, if all values in the data set are different, there is no value that repeats. As a result, the mode is not defined or can be considered to be non-existent.
In statistical terms, we can say that a data set with all unique values is amodal, meaning it does not have any mode. This concept is important for understanding how mode functions in descriptive statistics. It emphasizes that the mode is not just about identifying a number, but rather about the frequency of occurrences within a set.