What shoe size should a shop stock most of? Not the mean (might be 8.3 — no such size). The mode — the size that shows up most often. The only average that works for categories.
The mode is the value that appears most frequently in a data set. A data set can have one mode, several, or none.
Inventory planning, most-common diagnosis, popular vote, peak traffic hour — when you care about 'what happens most', the mode is your tool.
Types of mode
- Unimodal — one value appears most.
- Bimodal — two values tie for most frequent.
- Multimodal — three or more tie.
- No mode — every value appears the same number of times.
Mode of: red, blue, red, green, blue, red?
Mode of 3, 5, 7, 9?
Every value appears once. No mode.
The mode isn't always 'in the middle' or 'typical'. In 1, 1, 1, 50, 60, 70, the mode is 1 — at the very bottom of the data.
Mode is the only average you can use for non-numeric data (colours, brands, categories). Mean and median need numbers.
- Mode = most frequent value.
- Can be none, one, or many.
- The only average that works for categories.