=+13.32 ● An investigation of the relationship between traffic flow x (thousands of cars per 24 hr) and lead content y of bark on trees near the highway (mg/g dry weight)

yielded the accompanying data. A simple linear regression model was fit, and the resulting estimated regression line was 5 28.7 1 33.3x. Both residuals and standardized residuals are also given.

x 8.3 8.3 12.1 12.1 17.0 y 227 312 362 521 640 Residual 278.1 6.9 269.6 89.4 45.3 St. resid. 20.99 0.09 20.81 1.04 0.51