What is the mean (average)?

The mean is the sum of all values divided by the number of values. It's the most common measure of central tendency. Formula: μ = Σx/n. The mean is sensitive to outliers—extreme values can significantly affect it.

What's the difference between mean and median?

The median is the middle value when data is sorted. For odd counts, it's the middle number; for even counts, it's the average of the two middle numbers. The median is not affected by outliers, making it more representative for skewed distributions.

What is standard deviation?

Standard deviation measures how spread out numbers are from the mean. It's the square root of variance. A low standard deviation means values cluster around the mean; a high one means they're spread out. In normal distribution, ~68% of data falls within ±1 SD, ~95% within ±2 SD.

When to use sample vs population standard deviation?

Use population standard deviation (divide by n) when you have data for the entire population. Use sample standard deviation (divide by n-1) when you only have a sample—this provides an unbiased estimate. This calculator provides both.

What are quartiles useful for?

Quartiles divide data into four equal parts. Q1 (25th percentile), Q2 (median, 50th percentile), Q3 (75th percentile). They're used for box plots, detecting outliers (values beyond Q1-1.5×IQR or Q3+1.5×IQR), and understanding data distribution.

What do skewness and kurtosis tell us?

Skewness measures distribution asymmetry: positive skew = right tail longer, negative = left tail longer. Kurtosis measures tail 'heaviness': high kurtosis means more outliers, low kurtosis means flatter distribution. These help assess normality of your data.

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❓ Statistics Terms Explained

Term	Description
Mean	Average of all values. Sum divided by count.
Median	Middle value when sorted. Not affected by outliers.
Mode	Most frequent value(s). May have multiple or none.
Std Deviation	Measures data spread. Higher = more dispersed.
IQR	Interquartile Range (Q3-Q1). Middle 50% data spread.
Skewness	Asymmetry measure. Positive = right-skewed, negative = left-skewed.
Kurtosis	Tail heaviness. Higher = more outliers, lower = flatter.

⚠️ Results are for reference. Use professional statistical software for precise analysis.

📊 Statistics Calculator

How to Use the 📊 Statistics Calculator

📝 Enter Data

📋 Descriptive Statistics

📈 Distribution Info

🔢 Sorted Data

❓ Statistics Terms Explained