(a) Draw a scatter diagram of the data. What type of relation appears to exist between x and y?
(b) Find the quadratic regression equation y̅ = b0 + b1x + b2x2.
(c) Draw a residual plot against the fitted values, x, and x2. Also, draw a boxplot of the residuals. Are there any problems with the model?
(d) Interpret the coefficient of determination.
(e) Does the F-test indicate that we should reject H0: β1 = β2 = 0? Is either coefficient not significantly different from zero?
(f) Construct and interpret 95% confidence and prediction intervals for x = 4.
x ______________________ y
1 ............................... 25.1
1.5 ............................ 19.3
2.1 ............................ 13.9
3.6 ............................ 8.5
4.3 ............................ 7.7
5.9 ............................ 12.9
6.2 ............................ 14.3