Statistics

Standard deviation calculator for sample and population data. Find standard deviation, variance, mean, sum, and range from a list of numbers instantly.

Perform a Wilcoxon Rank Sum Test (Mann-Whitney U) for two independent samples. Get the U statistic, Z-score, and p-value instantly — no normality required.

Wilcoxon signed-rank test calculator for paired samples. Compare before-and-after measurements with W statistic, Z-score, and p-value — no normality assumption.

Calculate a Yates-corrected chi-square statistic for 2×2 contingency tables. Enter a, b, c, d cell counts and get the adjusted χ² value and p-value instantly.

Z-score calculator: find how many standard deviations a value is from the mean. Enter raw score, mean, and standard deviation to get z-score and interpretation.

One-sample and two-sample Z-test calculator for hypothesis testing. Enter sample mean, population SD, and sample size to get the Z-statistic and p-value.

Perform Tukey's HSD post-hoc test after ANOVA. Compare all group mean pairs to find statistically significant differences with one free online tool.

Explore the Two Envelopes Paradox interactively. Calculate expected values for switching or keeping, and understand the probability math behind this puzzle.

Calculate PDF, CDF, mean, variance, and interval probability for any uniform distribution. Enter the range parameters a and b to get instant results.

Calculate upper and lower fences using the IQR method to identify outliers in your dataset. Instantly find Q1, Q3, IQR, and all data points outside the fences.

Calculate the Upper Control Limit (UCL) for statistical process control charts. Enter raw data or summary stats to monitor process variation and quality.

Variance calculator for sample and population data. Computes variance, standard deviation, mean, median, mode, and IQR from any list of numbers instantly.

Venn diagram calculator for 2 and 3 sets. Find union, intersection, and exclusive regions instantly — ideal for set theory, probability, and survey analysis.

Wald test calculator for statistical significance. Enter parameter estimate, standard error, and alpha level to get the Wald statistic, z-score, and p-value.

Weibull distribution calculator for reliability analysis. Compute PDF, CDF, hazard rate, mean, median, and variance from shape and scale parameters instantly.

Weighted mean calculator for grades, finance, and surveys. Enter values and weights to compute the weighted average — supports any number of data points.

Sampling distribution of the sample mean calculator: find SE, z-score, and probability (less than, greater than, between) using the Central Limit Theorem.

Spearman's rank correlation calculator: compute ρ for two datasets. Measures monotonic relationships without normality requirements — ideal for ordinal data.

Standard deviation calculator: compute sample SD, population SD, mean, variance, and CV from any dataset. Enter numbers and get results instantly.

Standard deviation of sample mean (SEM) calculator: compute SEM, mean, variance, and SD from raw data. Enter comma-separated numbers to get results instantly.

Standard error calculator: compute SE from raw data or summary statistics. Includes confidence intervals at 90%, 95%, and 99% — free and accurate.

Calculate Relative Standard Deviation (RSD) and Coefficient of Variation (CV) instantly. Free statistical analysis tool for data dispersion and precision.

Perform one-way repeated measures ANOVA analysis. Enter subject data to get F-statistic, effect size (eta squared), and complete ANOVA table instantly.

Calculate linear regression residuals instantly. Enter X and Y values to get the regression line, predicted values, residuals, and R-squared for any dataset.

Calculate relative risk (RR), absolute risk reduction (ARR), and number needed to treat (NNT). Free online risk calculator for clinical trials and epidemiology.

Calculate AUC and plot ROC curves for binary classifiers. Input prediction scores and true labels to get sensitivity, specificity, and optimal threshold.

Roulette payout calculator for American and European wheels. Enter bet type and wager to get net winnings, total payout, payout odds, and win probability.

Relative Standard Error (RSE) calculator — divide standard error by the estimate to get a unit-free precision percentage and a qualitative reliability rating.

Sample size calculator using Cochran's formula. Enter confidence level, margin of error, and proportion to get the minimum sample size for reliable surveys.

Sampling distribution of the sample proportion calculator. Find mean, standard error, normality check, Z-score, and cumulative probabilities instantly.

Sampling error calculator for proportions and means. Enter sample data and confidence level to get the standard error and margin of error with FPC support.

Calculate exact and cumulative Poisson probabilities instantly. Find P(X=x), P(X≤x), P(X≥x) for any lambda and event count — free online statistics tool.

Fit data to a polynomial equation with this free curve fitting tool. Get the best-fit polynomial equation, R-squared value, and predict new values instantly.

Calculate the pooled standard deviation for two samples using sizes, means, and standard deviations. Accurate results for t-tests and statistical analysis.

Calculate population variance, standard deviation, and mean for any data set. Free online statistical dispersion tool — paste numbers and get results instantly.

Calculate post-test probability using Bayes' theorem. Enter prior probability, sensitivity, and specificity to find PPV, NPV, and likelihood ratios.

Calculate the F-statistic and p-value for comparing two sample variances. Enter group variances and sizes to run an ANOVA or F-ratio test instantly.

Perform an F-test for equality of two variances. Enter sample variances and sizes to get the F-statistic, p-value, and reject/fail-to-reject decision.

Calculate the probability of truly having a condition after a positive test. Enter prevalence, sensitivity, and specificity to see the false positive paradox.

Run Fisher's Exact Test on a 2×2 contingency table. Get one-tailed and two-tailed p-values plus the odds ratio — ideal for small sample sizes in research.

Create a frequency distribution table from any data set. Calculate frequency, relative frequency, cumulative frequency, mean, median, and standard deviation.