Prediction R-Squared Calculator
Prediction R-Squared with explicit assumptions and reproducible inputs.
Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Can be negative for poor predictions. This is unadjusted prediction R²; it is not automatically the square of a correlation coefficient.
Example Calculation
- Observed y: 1, 2, 3
- Predicted y: 1, 2, 3
Predictions identical to1,2,3 give zero residual error and R²=1.
Frequently asked questions
How do I use this calculator?
Enter observed y, predicted y. The result updates automatically. Use Reset to restore the example values.
What method does it use?
R²=1−Σ(y−ŷ)²/Σ(y−mean y)². Can be negative for poor predictions. This is unadjusted prediction R²; it is not automatically the square of a correlation coefficient.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.