60 tools
Statistics
Averages, spread, correlation and the tests that say whether a difference is real — each one showing the numbers it rests on.
Tools in this category
- StatisticsAverage CalculatorPaste a list of numbers and get the mean, median, sum, count, minimum, maximum and range.
- StatisticsWeighted Average CalculatorAverage a list of values where each one carries a different weight or coefficient.
- StatisticsStandard Deviation CalculatorHow spread out a set of numbers is, with the subtraction and the squaring laid out line by line.
- StatisticsT-Test CalculatorWhether the difference between two sets of numbers is bigger than chance would produce, with the p value and the size of the difference.
- StatisticsLinear Regression CalculatorThe straight line that fits a set of points best, with the equation, how much it explains, and a prediction.
- StatisticsMargin of Error CalculatorThe proportion your sample found, the margin of error around it, and the interval that follows — with the finite population correction when it applies.
- StatisticsCorrelation CalculatorHow closely two sets of numbers move together, by Pearson and by rank, with a confidence interval around the answer.
- StatisticsProbability CalculatorThe chance of both, either, neither or exactly one of two independent events.
- StatisticsQuartile CalculatorThe median, the quartiles, the interquartile range and the values Tukey's rule flags as outliers.
- StatisticsBayes' Theorem CalculatorWhat a positive result really means, once the rarity of the thing being tested for is taken into account.
- StatisticsChi-Square CalculatorWhether counts differ from what you expected, or whether two categories are related, with the p value and the strength of the link.
- StatisticsCombinations and Permutations CalculatorHow many ways k items can be chosen from n, with and without counting the order.
- StatisticsMean, Median and Mode CalculatorThe three averages of a set of numbers, plus the range and the count.
- StatisticsANOVA CalculatorWhether three or more groups really differ, by comparing the variation between them against the variation inside them.
- StatisticsMoving Average CalculatorSmooth a bumpy series of numbers by averaging each value with the ones before it, and see where the trend is heading.
- StatisticsStatistical Power CalculatorWhether your study is big enough to find the difference you are looking for, and how many people it would take.
- StatisticsSkewness and Kurtosis CalculatorWhich way a distribution leans and how heavy its tails are, with the standard errors that say whether either is real.
- StatisticsPermutations with Repetition CalculatorHow many arrangements are possible when things can repeat, or when the set you are rearranging already contains duplicates.
- StatisticsCoefficient of Variation CalculatorSpread as a percentage of the mean, so two things measured on different scales can be compared for variability.
- StatisticsDice Probability CalculatorChance of rolling at least one chosen face, the expected total, and the odds of all dice matching.
- StatisticsStratified Sampling CalculatorHow many people to draw from each group so that the sample mirrors the population, with the rounding handled properly.
- StatisticsBirthday Problem CalculatorChance that two of a group share a value, with the number of pairs and the group size for even odds.
- StatisticsConfidence Interval CalculatorMargin of error and confidence interval for a sample mean, with the standard error and the sample size for half the margin.
- StatisticsNormal Distribution Probability CalculatorProbability below, above and within a value on a normal curve, with the z-score and the odds of exceeding it.
- StatisticsSample Size CalculatorSample size for a survey or inspection at a chosen confidence level and margin of error.
- StatisticsProbability of At Least One CalculatorChance that an event happens at least once over repeated independent tries, with the tries needed for even odds.
- StatisticsA/B Test Significance CalculatorWhether the difference in conversion rate between two versions of a page, email or ad is likely to be real or just chance, with the p-value and z statistic.
- StatisticsOdds to Probability CalculatorImplied probability from odds, in decimal and fractional form, with the return on a stake.
- StatisticsZ-Score CalculatorHow many standard deviations a value sits from the mean.
- StatisticsExpected Value CalculatorExpected value of three possible outcomes, with the variance and standard deviation of the result.
- StatisticsSensitivity and Specificity Calculator (Diagnostic Test Accuracy, PPV, NPV)Sensitivity, specificity, predictive values, accuracy and likelihood ratios from the four counts of a test result table, and the predictive values at any other prevalence.
- StatisticsPoisson Distribution CalculatorProbability of exactly k events, of none, and of at least one, when the average rate is known.
- StatisticsBinomial Probability CalculatorProbability of exactly k successes in n independent trials, with the expected value.
- StatisticsBest-of Series Probability Calculator (Playoffs: Best of 3, 5, 7)The chance that a team wins a best-of-3, 5, 7 or 9 series, and how many games it is likely to take, from its chance of winning one game.
- StatisticsCohen's d Calculator (Effect Size Between Two Groups)Cohen's d and Hedges' g from the means, standard deviations and sizes of two groups, with a 95 % interval, the common-language effect size and the usual small/medium/large label.
- StatisticsCombined Standard Deviation Calculator (Merging Two or Three Groups)The mean and standard deviation of several groups put together, from each group's size, mean and standard deviation — without needing the raw data.
- StatisticsError Propagation Calculator (Uncertainty of Sums, Products, Quotients, Powers)The uncertainty of A + B, A − B, A × B, A ÷ B and Aⁿ from the uncertainties of A and B, using the standard rules for independent errors.
- StatisticsSample Size for Comparing Two ProportionsHow many people you need in each group to detect a difference between two rates.
- StatisticsSampling Distribution of the Mean Calculator (Standard Error and Sample-Mean Probabilities)The standard error of a sample mean, the chance that a sample of size n averages above, below or this far from the true mean, and the range holding 95 % of sample means.
- StatisticsSample Size for Comparing Two MeansHow many subjects you need per group to detect a given difference between two averages.
- StatisticsAcceptance Sampling Calculator (Single Sampling Plan, OC Curve Point)Chance that a lot passes inspection for a plan of n items checked and c defects allowed, with the average outgoing quality and the average number of items inspected.
- StatisticsCohen's Kappa Calculator (Agreement Between Two Raters)Cohen's kappa, observed and chance agreement, an approximate 95 % interval and the Landis–Koch label for two raters who each said yes or no to the same items.
- StatisticsCorrelation Confidence Interval Calculator (Fisher z Transformation)A confidence interval for the true correlation behind a sample r, by Fisher's z transformation, with an approximate p-value for r = 0 and the shared variance r².
- StatisticsCoupon Collector Calculator (How Many Packs to Complete the Set)How many random draws you need on average to collect every different item in a set, or a given number of them, with the typical spread.
- StatisticsEmpirical Rule Calculator (68–95–99.7) and Chebyshev's InequalityThe range within k standard deviations of the mean, the share of data inside it if the data are normal, and the weaker share guaranteed for any shape of data.
- StatisticsExponential Distribution Calculator (Waiting Times)Chance that the next event — a customer, a failure, a call — comes within a given time when events arrive at random at a known average rate.
- StatisticsExponential Smoothing Forecast Calculator (Simple, Next-Period Demand)Next-period forecast from five periods of actual values with simple exponential smoothing, plus the average error and bias of the forecasts it would have made.
- StatisticsGambler's Ruin Calculator (Chance of Reaching Your Goal Before Going Broke)The chance of reaching a target stake before losing everything, and how long it takes, when you bet one unit at a time at fixed odds.
- StatisticsHerfindahl-Hirschman Index (HHI) Calculator (Market Concentration)Market concentration from up to six firms' market shares, the equivalent number of equal-sized firms, and how much a merger of the first two would raise the index.
- StatisticsLaspeyres, Paasche and Fisher Price Index Calculator (Cost of Living Basket)Price index of a small basket of goods from base-period and current prices and quantities, by the Laspeyres, Paasche and Fisher methods.
- StatisticsLognormal Distribution Calculator (Mean, Median, Mode, Probability)Mean, median, mode and standard deviation of a lognormal variable, the μ and σ behind it, and the chance that it stays at or below any value.
- StatisticsNegative Binomial Calculator (Trials Until the r-th Success)The chance of getting your r-th success on a given trial or within a given number of trials, and how many trials it takes on average.
- StatisticsPareto Principle Calculator (80/20 Rule, Pareto Index and Gini)Fit a Pareto distribution to a rule like 'the top 20 % hold 80 %' and read off the Pareto index, the Gini coefficient and the shares held by the top 1 %, top 10 % and bottom half.
- StatisticsRelative Risk and Odds Ratio Calculator (2×2 Table)Relative risk, odds ratio, risk difference and number needed to treat from a 2×2 table, with 95 % confidence intervals.
- StatisticsWilson Score Interval Calculator (Confidence Interval for a Proportion)A confidence interval for a percentage from successes out of trials, by the Wilson method, with the simple textbook interval alongside to show where that one goes wrong.
- StatisticsZero Events Upper Limit Calculator (Rule of Three)After n trials with no failures, accidents or side effects, how high the true rate can still be at your confidence level — and how many clean trials it takes to rule out a given rate.
- StatisticsBenford's Law Calculator (Expected First-Digit Frequencies)How often a number should start with each digit in real-world data, the expected count in your data, and a z-test of whether your own count is too far off.
- StatisticsHypergeometric Probability CalculatorOdds of drawing a given number of the right things, when you draw without putting them back.
- StatisticsTriangular Distribution Calculator (Best, Most Likely, Worst Case)Mean, standard deviation, median, the chance of staying under a value and any percentile of a triangular distribution defined by a minimum, a most likely value and a maximum.
- StatisticsTwo-State Markov Chain Calculator (Weather Model, Steady State)The chance of being in each of two states after any number of steps, and the long-run share of time in each, from the two switching probabilities.