Suppose the following are the seasonal indices for the first three quarters of the year for a quarterly series:
Quarter
Seasonal Index
Q1
74.7
Q2
88.2
Q3
107.7
Remember that the seasonal indices should average 100 so you should be able to infer the seasonal index for Q4.
Furthermore, suppose that the estimated coeffcients from a regression of the deseasonalized series on Time are given below:
Coefficients
Intercept
2,579
Time
52.5
What is the trend projection of the series for period 107?