Problem When cars from Korean automobile manufacturers started coming to the United States they were given very poor quality ratings. That started changing several years ago. J.D. Power and Associates generates a widely respected report on initial quality. The improved quality started being seen in the 2004 Initial Quality Study. Results were based on responses from more than 62.000 purchasers and lessors of new-model-year cars and trucks, who were surveyed after 90 days of ownership. Initial quality is measured by the number of problems per 100 vehicles (PP100). The PP100 data from the interval 1998-2004 follow. 1998 1999 2000 2001 2002 2003 2004 Korean 272 227 222 214 172 152 117 Domestic 182 177 164 153 | 137 | 135 123 European 158 171 154 141 137 136 122 a Produce a regression equation to predict the PP100 for vehicles in the model y; = Bo + B + Byty + €: where ſi if Domestic J1 if European 10 if not Domestic and 12 = {0 if not European b. Interpret the parameters 30. 31 and 32 in the model given in part a c. Conduct a test of hypothesis using the model in part a to determine if the average PP100 is the same for the three international automobile production regions. Problem Consider the following values for the dependent and independent variables: < y 10 15 25 44 79 112 5 15 40 50 60 80 . J a Develop a scatter plot of the data Does the plot suggest a linear or nonlinear relationship between the dependent and independent variables? b. Develop an estimated linear regression equation for the data. Is the relationship significant? Test at an a = 0.05 level. c. Develop a regression equation of the form ý – bg + b*t + bxr? Does this equation provide a better fit to the data than that found in part b?
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