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Statistics Calculators

20 free tools for data analysis. From basic mean and standard deviation to complex hypothesis testing.

Basics & Means Variation & Spread Probability & Tests

FAQ

X-Bar vs. Mu?

Use "Sample Mean" for subsets (x̄) and "Population Mean" (μ) if you have data for the entire group.

Which correlation?

The Pearson Correlation (r) is best for linear relationships between two continuous variables.

Outlier rule?

Our Outlier Calculator uses the 1.5×IQR rule to flag data points.

What does a P-Value tell me?

It measures the evidence against the null hypothesis. A P-value lower than 0.05 usually indicates statistical significance.

Variance vs. Standard Deviation?

Variance (σ²) is the average squared deviation, while Standard Deviation (σ) is the square root, expressed in the same units as your data.

When to use Geometric Mean?

Use it for growth rates, percentages, or financial returns where effects are multiplicative rather than additive.

Why divide by n-1 for Sample Variance?

This is Bessel's Correction. It corrects the bias in the estimation of the population variance when using a smaller sample.