Statistics Calculator
Compute summary statistics (mean, median, mode, variance, standard deviation, quartiles, IQR) for a list of numbers.
Inputs
Mean
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Median
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Std deviation (sample, n-1)
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Std deviation (population)
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Variance (sample)
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Min
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Max
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Range
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1st quartile
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3rd quartile
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Interquartile range
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Count
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About Statistics Calculator
Sample vs population std dev
Sample (divide by n−1) is an unbiased estimator of the population std dev when you only have a sample. Population (divide by n) assumes you have the entire population. Use sample unless you’re certain you have every member.
Quartiles
Q1 (25th percentile): a quarter of values fall below. Q2 = median. Q3 (75th): three quarters below. IQR = Q3 − Q1 captures the middle 50% — useful for identifying outliers (values beyond 1.5×IQR from quartiles).
When the mean misleads
Skewed data (income, response times, web traffic) often has mean far above median because of a few huge values. Always report median alongside mean for non-symmetric data.