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 2

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

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

b. Are there any outliers? If so, identify the observation numbers and delete the observation and repeat part a.

c. Examine the residual plots and comment on the fit of the model. Are there any fit issues?

d. Perform a log transformation on the variable Carbon Monoxideusing Log(Carbon Monoxide)as the dependent variable. Explain why this log transformation is appropriate. Report the parameter estimates.

e. Is Nicotineuseful (use α = 0.05) in predicating Log(Carbon Monoxide)? Why?

f. What percentage of the variation in Log(Carbon Monoxide) is explained by Nicotine? Is that high or low?

g. What is the predicted value for Carbon Monoxide when Nicotine is 1.00? Give a 95% prediction interval for this estimate.

Answer 1