Please check attachement about introduction of forecasting and decision analysis.
There is no limit on topic chosen that you can choose any research topic. The only requirement is you choose any forecast and do the recent data analysis with SPSS and output. Making output in report analyse report including the SPSS output data, code and pictures .
For example, you can forecast the weather, the company sales or profit, etc. But no matter on which topic, you should use the recent years data to do analysis under different forecast model. Finally to compare these different models.
I attached the useful materials for the models and might help. Please read and do following tge example exercise.