VG1
statistikk
Quiz
Mean, median and mode
Mean, median and mode are three ways to describe the centre of a dataset. They give different perspectives and are used in different situations.
Mean (arithmetic average)
x̄ = (x₁ + x₂ + ... + xₙ) / n
Dataset: 4, 7, 3, 9, 2
Mean = 25/5 = 5
Mean = 25/5 = 5
Median
The middle value when data is sorted.
Sorted: 2, 3, 4, 7, 9 → Median = 4
Mode
The value that occurs most often.
3, 5, 5, 7, 9, 5 → Mode = 5
When to use which
| Measure | Use when |
|---|---|
| Mean | Evenly distributed data without outliers |
| Median | Data with outliers (e.g. income) |
| Mode | Categorical data |
Outliers strongly affect the mean! Use median when data is skewed.
Whatever property we examine, nature always shows a tendency toward the mean.
— Francis Galton (1822–1911)
🧠 Test yourself
Question 1 of 3
Dataset: 2, 4, 6, 8, 10. What is the mean?