Fitting and interpreting the least-squares line, residual plots, interpolation and extrapolation

What this note covers

1. What the least-squares line actually is
2. Obtaining and writing the equation
3. Interpreting the slope in context
4. Interpreting the intercept, and when it means nothing
5. Residuals: observed minus predicted
6. Residual plots and the appropriateness of a linear model
7. Prediction, interpolation and extrapolation
8. How this is examined in the WACE paper

8 sections · 12 key terms & formulas · 6 common mistakes