Question

The cigarette data set (partially given below) presents data on tar, nicotine, weight (in grams) and carbon monoxide contents (in milligrams) for a sample of 25 (filter) brands of cigarettes tested in a recent year.

Tar (x1)	Nicotine (x2)	Weight (x3)	Carbon Monoxide (y)
14.1	0.86	0.9853	13.6
.	.	.	.
.	.	.	.
12.0	0.82	1.1184	14.9

Question 3

Answer the following for the variables Carbon Monoxide (response variable) and Weight(predictor variable).

a. Fit the regression line. Report the parameter estimates.

b. Examine the residual plots and comment on the fit of the model. Are there any fit issues? Are there any outliers? If so, identify the observation numbers and delete the observation and repeat part a.

c. Is Weightuseful (use α = 0.05) in predicating Carbon Monoxide? Why?

d. What percentage of the variation in Carbon Monoxide is explained by Weight? Is that high or low?

e. What is the predicted value for Carbon Monoxide when Weight is 1.0g? Give a 95% prediction interval for this estimate.

Answer 1