How to Calculate Variance
What is Variance?
Variance measures how spread out data values are from their mean. Standard deviation is the square root of variance and is in the same units as the original data.
Formula
- N
- N value — Variable used in the calculation
Step-by-Step Guide
- 1Population variance: σ² = Σ(xᵢ − μ)² / N
- 2Sample variance: s² = Σ(xᵢ − x̄)² / (n−1)
- 3Use n−1 (Bessel's correction) for sample data
- 4Standard deviation σ = √variance
Worked Examples
Frequently Asked Questions
What is Variance?
Variance measures how spread out data values are from their mean. Standard deviation is the square root of variance and is in the same units as the original data
How accurate is the Variance calculator?
The calculator uses the standard published formula for variance. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.
What units does the Variance calculator use?
This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Variance calculator use?
The core formula is: Population variance: σ² = Σ(xᵢ − μ)² / N. Each step in the calculation is shown so you can verify the result manually.
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