What is standard deviation?

Standard deviation measures the spread of data around the mean. A low standard deviation means data points are close to the mean; a high value indicates wider dispersion.

What are quartiles and IQR?

Quartiles divide data into four equal parts. The Interquartile Range (IQR) = Q3 – Q1, representing the middle 50% of data, useful for outlier detection.

Advanced Data Analysis

Statistics Calculator

Compute 15+ descriptive statistics including mean, median, mode, standard deviation, variance, quartiles, skewness, and more. Just paste your numbers.

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Mean (μ)

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Std Deviation (σ)

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Variance (σ²)

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Median

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Mode

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Range

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Count (n)

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📐 Quartiles & IQR

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Q2 (Median)

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IQR

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Skewness

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Kurtosis

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Sum

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Sum of Squares

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📖 Statistical Terms Explained

Standard Deviation (σ): Measures data dispersion around the mean. Lower = more consistent.
Variance (σ²): Square of standard deviation. Used in many statistical tests.
Quartiles (Q1, Q2, Q3): Divide sorted data into four equal parts. IQR = Q3 – Q1 (outlier detection).
Skewness: Asymmetry of distribution. Positive = right tail longer; negative = left tail longer.
Kurtosis: Tailedness of distribution. High kurtosis = more outliers.

🧠 Real‑World Applications

Quality control (std dev of product dimensions), finance (volatility of stock returns), education (test score analysis), healthcare (clinical trial variability), and machine learning (feature scaling).

Tip: Use our calculator to quickly check skewness before applying parametric tests.