The makers of the Lexus automobile have steadily increased their sales since their U.S. launch in 1989. However, the rate of increase changed in 1996 when Lexus introduced a line of trucks. The sales of Lexus from 1996 to 2005 are shown in the table:

a. Plot the data using a scatterplot. How would you describe the relationship between year and sales of Lexus?

b. Find the least-squares regression line relating the sales of Lexus to the year being measured?

c. Is there sufficient evidence to indicate that sales are linearly related to year? Use α = .05.

d. Predict the sales of Lexus for the year 2006 using a 95% prediction interval.

e. If they are available, examine the diagnostic plots to check the validity of the regression assumptions.

f. If you were to predict the sales of Lexus in the year 2015, what problems might arise with your prediction?

Transcribed Image Text:

Year 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 80 100 155 180 210 224 234 260 288 303 Sales (thousands of vehicles)