Statistics

Study Sheet

Statistics

Mean, median and spread

Two Kinds of Middle

Concept
The Big Idea
456789

The mean shares the total out equally. The median is the value in the middle once the data is in order. One outlier drags the mean but barely moves the median.

Tip
Even-sized sets

With an even count there is no single middle value, so the median is the average of the two middle numbers.

In Plain Terms & More Examples

Concept
In plain terms

The mean shares the total out equally; the median is the middle value once the numbers are in order.

Example
Mean of 4,6,8,104, 6, 8, 10

Total =28= 28, and 28÷4=728 \div 4 = 7, so the mean is 77.

Example
Median of 3,5,93, 5, 9

In order, the middle value is 55.