To access Rebuilding the Base, click on Extended Features on the Main Menu of IFs, and then select Rebuild Model Base.
Rebuilding the Base Case
If you have made substantive changes to, say, the regionalization of IFs, you will have to rebuild the base for those changes to take effect. Choose Model Change again from the Main Menu and choose the Rebuild Base sub-option. That may have two sub options – you want Rebuild Base, not Rebuild Historic Base (although if both are there, the regionalization change means that you should return later and also Rebuild the Historic Base). IFs will provide a short synopsis of what rebuilding the base will do and when you would want to do it. It then provides the Rebuild Base window – at this point, you can still change your mind and exit without rebuilding the base:
At this point you have changed the regionalization, but have not changed any of the raw country data, so check only the Regionalization box on this screen. Note that IFs will, however, automatically check the issue-area specific boxes, because it needs to create new regional values in each one of those. Normally you will want to rebuild the base case for as long a time period as possible, so leave the Last Year at 2100. When ready, touch the Rebuild Base command button.
Rebuilding the base case will take a while, because all country-specific data must be aggregated into regions. The preprocessor that does this also takes care to check consistency of various data series and to fill holes as necessary.
Running the Model to Fill the New Base Case
When the process is complete, you will be reminded that you must now run the model. Although all initial conditions and parameters have been placed into the base case, all computed values were set at 0 when you rebuilt the base. So Exit to the Main menu, go to Self-Managed Scenario Analysis, choose the Run option, and run the model for the longest time period possible (normally 2100).
Upon completion of the model run, you will have a working file with the computed variables, but the IFsBase.run file will still not include those computed variables. Because you have rebuilt the Base Case, the model will ask you if you want to save the results of your run (still in the Working File) as the new Base Case. Respond affirmatively to save the working file as IFsBase.run. These are the only circumstances under which IFs will allow you to save over the Base Case.
You should now have a Base Case that includes whatever changes you made to the regionalization of the model. You will be able to display any variable in IFs for the change you made.