Pearson Correlation

Pearson Correlation — how strongly do two things move together? Type your (x, y) pairs and instantly get Pearson's r, a significance test, a 95% confidence interval and R², with a scatter plot, a trend line and a strength gauge that puts r on a dial from −1 to +1. Fully offline. Pearson's r is one tidy number that says how strongly two variables rise and fall together in a straight-line way. It runs from −1 (perfect opposite) through 0 (no link) to +1 (perfect together). Taller people tend to weigh more; more study hours tend to mean higher marks. This app measures that link, tests whether it is real, and shows you the picture behind the number. No sign-up. No internet needed. No data collected. Just clear, instant statistics. WHAT YOU CAN DO • Calc — type each (x, y) pair into a clean editor (add or remove points with a tap) and instantly get r, the t-test p-value, the 95% confidence interval and R². • Gauge — see r on a red-to-green dial, and a scatter plot with the trend line so you can judge how tightly the dots hug the line. • Concept — learn what r measures, how big is "big" (effect size), how the significance test works, and two crucial warnings — with offline, beautifully typeset formulas that never overlap. • Sim — set a target r and the sample size with + / - steppered sliders, generate data, and see how the same correlation can be significant with many points but not with few. • Cases — load real correlations (height vs weight, study time vs grades and more) with one tap. WHAT YOU GET • Pearson's r and R² (the share of variance explained). • A significance test (t) with its p-value. • A 95% confidence interval for the true correlation. • A scatter plot, a trend line and a strength gauge. WHY YOU'LL LIKE IT • See AND measure — the scatter and gauge make r meaningful, not just a number. • Confidence interval, not just a point — know how sure you can be. • Honest warnings — r only sees straight-line links, and correlation is not causation. • Fully offline — every statistic, chart and formula works with no connection. • Hands-on — type exact pairs, or dial a correlation with sliders and + / - steppers. • Clean "Mocha & Teal" design, easy on the eyes. Two reminders the app keeps front and centre: r captures only LINEAR patterns (a perfect U-shape can give r ≈ 0), and a strong correlation does not prove one thing causes the other — a hidden third factor may drive both. Whether you are a student meeting correlation for the first time, a researcher checking a relationship, or anyone curious how two measures move together, Pearson Correlation gives you the number, the test and the picture in seconds. Download it, enter your pairs, and see how strong the link really is.