For most services, longer customer waiting times mean lower customer satisfaction. Suppose you have the following data to use for a simple linear regression analysis intended to link length of waiting time before speaking to a customer service representative (x) and customer satisfaction (y) for your company’s customer service department. (Customer satisfaction is measured by scoring customer responses in a follow up questionnaire.)

Show the data in a scatter diagram and use the least squares criterion to find the slope (b = ====) and the intercept (a) for the best fitting line. Sketch the least squares line in your scatter diagram. Use the line to estimate the change in customer satisfaction level for each five minute increase in waiting time.

Waiting Time (minutes) 20 Satisfaction Level 72 24 96 60 30 40