When creating formulas, you can choose when to run the formula and update your analysis. You can choose to update formulas only when dynamic update events occur, only when a forced update is done, only when the formula changes, or any combination of these options. By default, formulas are re-evaluated, and their results updated, every time one of the following events occurs:
One or more features are added, deleted, or changed by editing the map
A dynamic attribute's value is changed
One or more assumptions are changed and the changes
are applied by clicking the Apply
button 
A formula is created or changed and then saved
When you are creating or editing attributes or indicators you can choose when you want your formulas to run using the Formula tab. There are three choices – you can choose any one or a combination of the options:
When dynamic updates occur: Formulas will be re-evaluated when you change dynamic attributes or assumptions and click the Apply button . They will also be re-evaluated when you edit the map.
When a forced update occurs: Formulas will be re-evaluated when you click the Scenario 360 drop-down menu, point to Data, and click Update Analysis on the Scenario 360 toolbar. This option is usually used when you have your dynamic updates set to manually update (opposed to running them automatically).
When the formula changes: Formulas will be re-evaluated when you edit the formula and click the OK button.
If you choose to run your updates manually, click the Scenario 360 toolbar menu, point to Data, then click Update Analysis. This will allow you to select the scenarios, dynamic layers, and indicators you wish to update.
Only those formulas that use the affected components are re-evaluated. Under some circumstances, you may want to re-run the formulas for an entire analysis or for layers within the analysis. For more information, see Setting dynamic updates to run automatically or manually.