Following are the average yields of long-term new corporate bonds over a several-month period published by the Office of Market Finance of the U.S. Department of the Treasury.
a. Explore trends in these data by using regression trend analysis. How strong are the models? Is the quadratic model significantly stronger than the linear trend model?
b. Use a 4-month moving average to forecast values for each of the ensuing months.
c. Use simple exponential smoothing to forecast values for each of the ensuing months. Let α = .3 and then let α = .7. Which weight produces better forecasts?
d. Compute MAD for the forecasts obtained in parts (b) and (c) and compare the results.
e. Determine seasonal effects using decomposition on these data. Let the seasonal effects have four periods. After determining the seasonal indexes, de-seasonalize the data.