Summarising Data: Mode & Median

When we collect data, two simple numbers help summarise it:

• The mode is the value that appears most often. In $4, 7, 4, 9, 4, 7$ the number $4$ appears three times, more than any other, so the mode is $4$. Data can also have a mode that is a category (the most popular choice).
• The median is the middle value once the data is put in order. For $3, 9, 4, 7, 6$, first sort: $3, 4, 6, 7, 9$. The middle one is $6$, so the median is $6$.

Worked example. Test marks $7, 8, 7, 10, 7, 8$: the mark $7$ occurs most, so the mode is $7$.