AP Statistics / Unit 5: Regression Analysis
5.3 Linear Regression Models
Notes
A regression line $\hat y=a+bx$ predicts $y$ from $x$.
- Slope $b$: predicted change in $y$ per 1-unit increase in $x$.
- Intercept $a$: predicted $y$ when $x=0$ (may not make sense).
- Avoid extrapolation beyond the data's $x$-range.
Practice
$\hat y=20+3x$ for score vs hours. Interpret the slope.
Predicted change per unit of $x$.
Using that line, predicted score for 5 hours:
$20+15$.
Predicting for 50 hours when data went up to 10 hours is:
Outside the data range.
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