Illustrations on these topics are being developed and will appear soon on this web page. The letter l , attached to the name of the series, implies that the data are in logarithmic form. In GiveWin, the Tools menu enables you to select Graphics where you can graph various time series. Below are graphs of the log values of these series. These were created by selecting the variables in the Graphics menu.
All series have a clear trend and seasonal component.
An interesting shift in the level of oiGASl in the early seventies can be detected. It has a downward trend and the seasonal component seems to be rather constant over time. In the Formulate a model dialog, select ofuCOALl as the Y variable in the first window. Accept the default settings in the other dialogs leading to the estimation of a basic structural time series model. Finally the variances of the selected stochastic components are given.