Data input
Model, plot, and reference settings
Tolerance, outliers, and filters
Interactive plot
Observation error table
Formula used
Residual = Actual − Predicted Absolute Error = |Actual − Predicted| Squared Error = (Actual − Predicted)² Percentage Error = ((Actual − Predicted) / Actual) × 100 MAE = Σ|Actual − Predicted| / n MSE = Σ(Actual − Predicted)² / n RMSE = √MSE R² = 1 − [Σ(Actual − Predicted)² / Σ(Actual − Mean Actual)²] Adjusted R² = 1 − (1 − R²)(n − 1) / (n − p − 1)
How to use this calculator
- Paste rows or upload a CSV dataset.
- Keep one actual column and one prediction column.
- Add more prediction columns for model comparisons.
- Choose filters, tolerances, and outlier settings.
- Select a plot type and calculate results.
- Inspect points, tables, metrics, and warnings.
- Export the chart, data, or PDF report.
Example data structure
| Label | Group | Actual | Linear Model | Tree Model |
|---|---|---|---|---|
| H1 | Urban | 185000 | 179000 | 188500 |
| H2 | Urban | 220000 | 228000 | 219500 |
| H3 | Suburban | 265000 | 254000 | 269000 |
Interpretation guide
Points near the diagonal indicate accurate predictions. Points above it show overprediction. Points below it show underprediction.
Small residuals usually indicate better local accuracy. Systematic residual patterns reveal model bias. Large isolated errors may indicate outliers.
Use several metrics before selecting a model. R² alone can mislead. Error scale and business tolerance also matter.
Frequently asked questions
What does the diagonal line represent?
It represents perfect predictions where predicted values equal actual values.
What does a point above the line mean?
The model predicted a value greater than the observed value.
What does a point below the line mean?
The model predicted a value smaller than the observed value.
Which metric should I prioritize?
Choose metrics matching your error costs, units, and modeling objective.
Can I compare several models?
Yes. Add one prediction column for every model being compared.
How are zero actual values handled?
Percentage metrics omit zero actual values and display a warning.
Can outliers be excluded?
Yes. Select a detection method and exclude marked observations.
What is prediction bias?
It is the average predicted value minus the actual value.
Why use equal axis scaling?
Equal scaling prevents visual distortion around the perfect prediction line.
Is uploaded data sent to a server?
No. This calculator processes uploaded CSV data inside your browser.