statistics
Descriptive Statistics Calculator Paste a list of numbers to get the count, sum, mean, median, mode, range, variance and standard deviation. T-Test Calculator Enter your data to compute a t-test — one-sample, independent two-sample (Welch) or paired — with the t value, df and p-value. Percentile Calculator Find the value at any percentile in your data, with quartiles and the interquartile range. Z-Score Calculator Convert a value into a z-score and find its percentile and the probability of scoring above it. Permutations & Combinations Calculator Enter n and r to get the number of permutations, combinations and the factorial of n. Weighted Average Calculator Calculate a weighted average from values and their weights, with the simple average for comparison. Confidence Interval Calculator Calculate a confidence interval for a mean, with the margin of error and z critical value. Correlation Coefficient Calculator Paste paired x, y data to get Pearson's r, R², and a plain-language read on the strength and direction. Linear Regression Calculator Paste x, y data to find the best-fit line y = mx + b, its R², and predicted values for any x. Probability Calculator Combine independent event probabilities and find the chance of at least one success over trials. Sample Size Calculator Calculate the survey sample size needed from confidence level, margin of error and proportion. Coefficient of Variation Calculator Calculate the coefficient of variation of your data, for sample and population, with mean and std dev.