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Statistics Tests
Calculate statistical tests, p-values, confidence intervals, correlations, regression models, and more - enter your data and get accurate results instantly. Everything runs in your browser; nothing is uploaded.
Hypothesis Tests
Independent Two-Sample T-Test
Compare the means of two independent groups (Welch's or pooled).
CalculatePaired Samples T-Test
Compare two matched/repeated measurements from the same subjects.
CalculateOne-Sample Z-Test
Test a sample mean against a population mean with a known σ.
CalculateChi-Square Test of Independence
Test whether two categorical variables are associated, using a contingency table.
CalculateChi-Square Goodness-of-Fit Test
Test whether observed category counts match an expected distribution.
CalculateOne-Proportion Z-Test
Test a sample proportion against a hypothesized population proportion.
CalculateChi-Square Test for a Variance
Test a single population variance (or SD) against a hypothesized value.
CalculateMcNemar's Test
Test for a change in paired/matched categorical data (e.g. before vs after).
CalculateMann-Whitney U Test
Nonparametric alternative to the independent two-sample t-test.
CalculateDegrees of Freedom Calculator
df for t-tests, chi-square tests, and one-way ANOVA.
CalculateTest Statistic Calculator
Quick z or t statistic from a sample statistic, hypothesized value, and standard error.
CalculateDescriptive Statistics
Descriptive Statistics
Mean, median, mode, spread, quartiles, skewness, kurtosis, and more.
CalculateGeometric Mean Calculator
The nth root of the product of n positive values.
CalculateHarmonic Mean Calculator
n divided by the sum of the reciprocals of the values.
CalculateMean Absolute Deviation Calculator
Average absolute distance of each value from the mean.
CalculateMidrange Calculator
The midpoint between the minimum and maximum of a dataset.
CalculateChebyshev's Theorem Calculator
Minimum share of any dataset within k standard deviations of the mean.
CalculateClass Width Calculator
Class width for a grouped frequency distribution given a range and number of classes.
CalculatePoint Estimate Calculator
Point estimate of a population mean (x̄) or proportion (p̂).
CalculatePercentile Calculator
Find any percentile, decile, or quartile of a dataset.
CalculatePercentile Rank Calculator
Find what percentile a given value falls at within a dataset.
CalculateRSD Calculator
Relative standard deviation - SD expressed as a percentage of the mean.
CalculatePooled Variance Calculator
Combined variance estimate from two independent samples.
CalculateCorrelation
Regression
Multiple Linear Regression
Fit a model with several predictors and inspect each coefficient.
CalculateCoefficient of Determination Calculator
Standalone R² for a linear fit between two variables.
CalculatePrediction Interval Calculator
Interval for a new observation at a given x, from a simple linear regression.
CalculateResidual Calculator
Individual residuals (actual − predicted) for a set of paired values.
CalculateANOVA
Probability & Distributions
P-Value Calculator
Find the p-value for a z, t, chi-square, or F statistic.
CalculateNormal Distribution Calculator
z-scores, probabilities, percentiles, and the curve itself.
CalculateBinomial Probability Calculator
Exact P(X=k), P(X≤k), P(X≥k) for a binomial distribution.
CalculatePoisson Probability Calculator
Exact P(X=k), P(X≤k), P(X≥k) for a Poisson distribution.
CalculateProbability Calculator
P(A and B), P(A or B), and conditional probabilities for two events.
CalculateHypergeometric Calculator
Probability of k successes when sampling without replacement from a finite population.
CalculateEmpirical Probability Calculator
Observed favorable outcomes over total trials - also called relative frequency.
CalculateExpected Value Calculator
E(X) for a discrete random variable given its values and probabilities.
CalculateSampling Distribution Calculator
Mean and standard error of the sampling distribution of x̄ (Central Limit Theorem).
CalculateStandard Error Calculator
Standard error of a sample mean or a sample proportion.
CalculateCritical Value Calculator
z*, t*, χ²*, or F* critical values for a given α and degrees of freedom.
CalculateRaw Score Calculator
Convert between a z-score and a raw score for a given mean and SD.
CalculateConfidence Intervals
Confidence Interval Calculator
CI for a mean, a proportion, or the difference between two of either.
CalculateEffect Size
Effect Size Calculator
Cohen's d, Hedges' g, r, eta squared, partial eta squared, or Cramer's V.
CalculateSample Size
Sample Size / Power Calculator
Find the sample size you need for a target power and effect size.
CalculateCombinatorics
Applied Statistics
Shannon Diversity Index Calculator
Diversity and evenness across categories from their counts.
CalculateAccuracy Calculator
Accuracy, precision, recall, and F1 from a confusion matrix.
CalculateRelative Risk Calculator
Risk ratio between an exposed and an unexposed group from a 2×2 table.
CalculateError Propagation Calculator
Propagate measurement uncertainty through addition, subtraction, multiplication, or division.
CalculatePERT Calculator
Expected duration and SD from optimistic, most likely, and pessimistic estimates.
CalculatePlots & Visualization
Empirical Rule Calculator
68-95-99.7% ranges for a normal distribution, with the curve plotted.
CalculateStem and Leaf Plot Calculator
Build a stem-and-leaf display from a dataset.
CalculateBox Plot Calculator
Five-number summary with a rendered box-and-whisker plot.
CalculateScatter Plot Maker
Plot paired data with an optional least-squares trend line.
CalculateResidual Plot Calculator
Plot regression residuals against x to check the fit.
CalculatePie Chart Calculator
Turn category counts into a pie chart with percentage shares.
Calculate