Statistics

ANOVA Calculator

Compare three or more independent groups with a one-way ANOVA calculator that returns the F statistic, p-value, ANOVA table, group means, effect sizes.

Binomial Distribution Calculator

Calculate exact, cumulative, upper-tail, between-range, and exact two-sided binomial-test probabilities from n, k, and p.

Central Limit Theorem Calculator

Use this central limit theorem calculator to compute standard error, sample-mean probability ranges, confidence intervals.

Chi-Square Calculator

Run a chi-square calculator for goodness-of-fit or independence tests with p-value, expected counts, selected-alpha decision, contribution rows.

Chi-Square to P-Value Calculator

Convert a chi-square statistic and degrees of freedom into the right-tail p-value.

Confidence Interval Calculator

Calculate confidence intervals for means or proportions from sample statistics and confidence level, with z or t mean intervals, margin of error, Wilson checks.

Correlation Calculator

Calculate Pearson or Spearman correlation for paired data, then compare both methods, inspect a scatter plot, and review R², t-statistic, p-value.

Covariance Calculator

Calculate sample covariance, population covariance, Pearson r, centered-product rows, and paired summary statistics from separate X/Y series or pasted X,Y rows.

Critical Value Calculator

Find z, t, chi-square, and F critical values by significance level, confidence shortcut, tail type, and degrees of freedom.

Empirical Rule Calculator

Use the empirical rule calculator to find 68-95-99.7 normal-distribution bands, exact probabilities, tail areas, z-score context, and Chebyshev bounds.

Error Function Calculator

Calculate erf(x), erfc(x), and the standard normal CDF from any input value.

Geometric Mean Calculator

Calculate geometric mean for positive growth factors, ratios, returns, and compound averages, with log-sum steps and arithmetic mean comparison.

Harmonic Mean Calculator

Calculate the harmonic mean of positive rates or per-unit values with reciprocal steps, formula substitution.

Hazard Ratio Calculator

Estimate an approximate hazard ratio from same-horizon treatment and control event counts, with confidence interval, event risks, and absolute risk difference.

Margin of Error Calculator

Use this margin of error calculator to estimate survey precision from sample size, confidence level, and expected proportion.

Mean Absolute Deviation Calculator

Calculate the mean absolute deviation (MAD) as a robust measure of spread — the average distance of each value from the mean.

Normal Distribution Calculator

Use this normal distribution calculator to find left-tail, right-tail, two-tailed, and between-two-values probability for any bell curve.

Normality Test Calculator

Run a normality test calculator with Jarque-Bera p-value, Shapiro-Wilk-style W, Q-Q fit, skewness, kurtosis, alpha thresholds, and next-step guidance.

Odds Ratio Calculator

Calculate an odds ratio from a 2x2 table with confidence interval, p-value, zero-cell correction, and odds ratio versus relative risk guidance.

P-value Calculator

Calculate p-values from z-scores, t statistics, chi-square statistics, and F statistics with one-tailed or two-tailed options, alpha-level decisions.

P-Value to Z-Score Calculator

Convert a p-value to the matching z critical value for left-tailed, right-tailed, or two-tailed normal tests.

Percentile Calculator

Use this percentile calculator to find percentile values from a dataset, compare linear interpolation with nearest rank, view every-fifth cutoffs.

Poisson Distribution Calculator

Calculate exact, at-most, at-least, greater-than, and between-count Poisson probabilities from λ, k, and interval scaling, with mean, variance.

Relative Risk Calculator

Calculate relative risk (risk ratio), confidence interval, absolute risk difference, NNT, and NNH from a 2x2 cohort or trial table.

Sample Ratio Mismatch Calculator

Detect sample ratio mismatch in A/B tests by comparing observed vs expected group sizes with a chi-square test.

Sample Size Calculator

Estimate the required completed survey responses for proportion-based surveys from confidence level, margin of error, expected proportion.

Severity Calculator

Calculate a risk severity score from probability and impact ratings, with classification and interpretation.

Statistics Calculator

Calculate descriptive statistics from one dataset.

T Test Calculator

Perform one-sample and two-sample Welch's t-tests on raw data, then review the t-statistic, p-value, degrees of freedom.

Z-score Calculator

Use this z score calculator to compute a standard score or solve backward for the raw value, mean, or standard deviation.

Z-Score to P-Value Calculator

Convert a z-score to a one-tailed or two-tailed p-value using the standard normal distribution.