Jim Jackson, a rate analyst for the Washington Water Power Company, is preparing for a rate case and needs to forecast electric residential revenue for 1996. Jim decides to investigate three potential predictor variables: residential use per kilowatt-hour (kWh). residential charge per kWh (cents/kWh). and number of residential electric customers. He collects data from 1968 to 1995. The data are shown in Table P-11. Jim testified before the Idaho Rate Commission and was asked if serial correlation was a problem. He didn't know the answer and has asked you to write a response to the commission's question.