Learn Statistics
Statistics calculators help you find averages, measure spread, analyze distributions, and interpret data. Explore our guides below to understand the formulas behind these statistical tools.
Guides
Understanding the Normal Distribution
Learn what the normal distribution is, why it matters in statistics, and how to use the bell curve for probability calculations, z-scores, and real-world data analysis.
Read guideHow to Calculate Confidence Intervals
Step-by-step guide to calculating confidence intervals. Learn when to use z-intervals vs. t-intervals, how to choose a confidence level, and how to interpret the results.
Read guideRegression Analysis Guide
Comprehensive guide to regression analysis. Learn how linear regression works, how to interpret slope and intercept, R-squared, residuals, and when to use regression.
Read guideHypothesis Testing Guide
Learn how hypothesis testing works step by step. Covers null and alternative hypotheses, test statistics, p-values, significance levels, and common pitfalls to avoid.
Read guideHow to Calculate Z-Score
Learn how to calculate a z-score step by step. Understand the z-score formula, what it means, and how to use it to compare data points across different distributions.
Read guideHow to Calculate Correlation Coefficient
Understand how to calculate the Pearson correlation coefficient r from scratch. Learn the formula, step-by-step process, and how to interpret the strength and direction of a linear relationship.
Read guideHow to Calculate Confidence Intervals
Learn how to calculate confidence intervals for a population mean. This guide explains the formula, choosing the right critical value, and correctly interpreting what a confidence interval means.
Read guideHow to Perform a T-Test
Learn how to perform one-sample, two-sample, and paired t-tests. This guide covers the t-test formula, degrees of freedom, p-values, and when to use each type of t-test.
Read guideHow to Calculate Regression Analysis
Learn how to perform simple linear regression analysis. This guide covers the least squares method, calculating slope and intercept, interpreting regression output, and assessing model fit with R².
Read guideHow to Calculate Variance
Learn how to calculate population and sample variance step by step. Understand the variance formula, why we divide by n−1 for samples, and how variance relates to standard deviation.
Read guideHow to Calculate Percentiles and Quartiles
Learn how to calculate percentiles and quartiles from a dataset. This guide explains the percentile rank formula, the interquartile range, and how these measures describe data distribution.
Read guideHow to Calculate Chi-Square Test
Learn how to perform a chi-square test of independence and goodness-of-fit. This guide explains the chi-square formula, how to build a contingency table, and how to interpret results using degrees of freedom.
Read guideHow to Calculate Sample Size
Learn how to calculate the required sample size for surveys and experiments. This guide covers the formula using margin of error, confidence level, and population proportion to determine how many subjects you need.
Read guideHow to Calculate Normal Distribution
Learn how the normal distribution works and how to calculate probabilities using it. This guide covers the probability density function, the empirical rule, standardization, and using z-tables to find area under the curve.
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