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Dictionary: Mean
The mean is the sum of all values divided by the number of values — the most common measure of centre.
x̄ = (x₁ + x₂ + ... + xₙ) / n
The mean gives one number that represents the whole dataset. It is strongly affected by outliers.
Example: 4, 7, 3, 9, 2 → Mean = 25/5 = 5
Remember: Use median when there are outliers — e.g. salaries in a company.
Whatever property we examine, nature always shows a tendency toward the mean.
— Francis Galton (1822–1911)
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