Scatter Plot

Know which of your numbers are really related, how strongly, and what curve best describes them. Correlation and regression for up to four sets of data, in your pocket or at your desk.

Free to use as long as you want: type in your own data, or try the built-in example data, and see full, real results. Check it against your own known data before you ever need to unlock anything.

Enter up to four columns of data, labelled A to D. The Correlation Matrix shows every pair at a glance, marks the strongest, and lets you tap any pair to analyse it. The app tests six curve types (linear, quadratic, cubic, exponential, power and logarithmic), picks the best fit, and shows its equation with R², adjusted R² and, for linear fits, a p-value. The chart adds an approximate 95% prediction band so you can see how much scatter to expect around the curve, and you can type in a value of X to read the matching Y from the best fit equation.

Honest about what the numbers mean. Every result is labelled as a weak, moderate or strong correlation. The app warns you when a single point is driving the result, and it switches the calculator off when the correlation is weak. Info buttons and a plain language reference page explain r, R², adjusted R², p-values and the fit types, with a worked example of why a strong correlation does not prove that one thing causes another.

Capture your data the way that suits the moment. Typing by hand is free. One unlock, with no subscription, reduces your typing:

Photograph a sheet and crop to the numbers
Choose an image from your photos
Speak the data aloud

Anything the photo reader is unsure about is highlighted for you to double-check.

The same unlock adds PDF reports with the chart, equation and statistics, CSV export, and saved run history.
Reading a column back to you, to cross-check against a paper record, is free.

Scatter Plot works as a pure mathematical tool, finding the equation that best relates any two sets of numbers, whatever they represent.

Two ways it's actually been used in real life:

Investigating whether a process input is really driving a process outcome. Put the input in one column and the outcome in another, and see whether the fit is strong enough to matter, or whether that input probably isn't the main driver after all.

Checking agreement between machines or measurement methods. Put a set of calibrated reference samples in column A, then each machine's readings on those same samples in another column. A strong, close-to-1:1 fit says that machine is tracking the reference well; a weak or skewed one is worth a closer look. Think of it as a quick, practical correlation check before starting a production line, not a replacement for a full Measurement System Analysis (Gauge R&R).

Built to work on your device. No account, no servers, and no data collected by the app. Calculations, charts and scanning need no internet connection, and speech recognition runs on your phone wherever your device supports it. Your camera, microphone, and readings are yours alone, and a report leaves your phone only if you choose to share it.

Built by a Six Sigma Black Belt with 35 years in manufacturing, as a companion to the Process Capability Calculator, for quality engineers, manufacturing professionals, students, and anyone who needs a fast, trustworthy correlation check without a desktop spreadsheet.

Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/