Numbers and measures
Weighted average
An average where each value counts in proportion to its weight, such as how many items it covers.
- Numbers and measures
Definition
An average where each value counts in proportion to its weight, such as how many items it covers. Multiply each value by its weight, add them up and divide by the total weight. A plain average of group averages is usually wrong when the groups differ in size.
Also called
Weighted mean
Example
Alta Sky Centre earned NOK 753 per individual admission (125,000 admissions) and NOK 963 per school or group participant (20,000). The weighted average is about NOK 782. The plain average of the two figures is NOK 858, which overstates it.
Alta Sky Centre AS is a fictional company created for Insyt.
See how it works
(20 × 90 + 80 × 60) ÷ 100 = 66, not 75.
Check your understanding
Common mistake: A plain average of group averages is misleading when group sizes differ.
Why is the overall average closer to the larger group's score?
Show explanation
Because the larger group contributes more observations.
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