Definition: The mode is the value that appears most often in a data set, and a set may have one mode, several modes, or none.
What is the mode?
The mode names the most popular value. It is the only measure of center that works for categories, like favorite color.
How do you find it?
Count how often each value occurs. In the shoe sizes 6, 7, 7, 8, 8, 8, 9, 10, the size 8 appears three times, more than any other. The mode is 8.
Can there be more than one?
Yes. The data 2, 2, 5, 5, 9 has two modes, 2 and 5. If every value appears exactly once, as in 3, 4, 6, 11, there is no mode.
How does it differ from mean and median?
The mean adds, the median locates the middle, and the mode counts. A store restocking T-shirts cares about the mode size, because the best seller matters more than the average size.
What is a common mistake?
Reporting how many times the value occurs instead of the value itself. In the shoe data, the mode is 8, not 3.