The Census Bureau of the Department of Commerce released the U.S. retail e-commerce sales (“Quarterly Retail E-Commerce Sales 1st Quarter 2006,” May 18, 2006) for the period of Fourth Quarter 1999 through Fourth Quarter 2008. The file titled E-Commerce contains those data.
a. Produce a time-series plot of this data. Indicate the time-series components that exist in the data.
b. Conduct a test of hypothesis to determine if there exists a linear trend in these data. Use a significance level of 0.10 and the p -value approach.
c. Provide forecasts for the e-commerce retail sales for the next four quarters.
d. Presume the next four quarters exhibit e-commerce retail sales of $35,916, $36,432, $35,096, and $36,807, respectively. Produce the forecast bias. Interpret this number in the context of this exercise.