In Problem 12.7 on page 424, you used the plate gap on the bag sealing equipment to predict the tear rating of a bag of coffee. Perform a residual analysis for these data (stored in Starbucks). Based on these results, evaluate whether the assumptions of regression have been seriously violated.

In Problem 12.7

Starbucks Coffee Co. uses a data based approach to improving the quality and customer satisfaction of its products. When survey data indicated that Starbucks needed to improve its package sealing process, an experiment was conducted to determine the factors in the bag sealing equipment that might be affecting the ease of opening the bag without tearing the inner liner of the bag. (Data extracted from L. Johnson and S. Burrows, “For Starbucks, It’s in the Bag,” Quality Progress, March 2011, pp. 17–23.) One factor that could affect the rating of the ability of the bag to resist tears was the plate gap on the bag sealing equipment. Data were collected on 19 bags in which the plate gap was varied. The results are stored in Starbucks.