When you click Next in the Objectives panel, the Decision Variables panel opens, similar to Figure 25, Decision Variables Panel with Cell Locations, Portfolio Allocation Example. It lists every decision variable, frozen or not, defined in all open Microsoft Excel workbooks.
The next step of the optimization process is selecting decision variables to optimize. The value of each decision variable changes with each simulation until OptQuest finds values that yield the best objective. For some analyses, you may fix the values of certain decision variables and optimize the rest.
By default, all decision variables in all open workbooks are shown, even those that are frozen in your model. Frozen decision variables have a check in the Freeze column. If you want, you can clear them and include them in the optimization. Be aware, though, that if you freeze or unfreeze a decision variable, you are also changing it in your model.
OptQuest uses the limits, base case (start value), and decision variable type you entered when you defined the decision variables.
If you select Show Cell Locations, the following additional columns are displayed in the Decision Variables panel: Cell Address, Worksheet, and Workbook.
To confirm and change selections:
Review the listed variables. Select Freeze for any that you do not want to include in the OptQuest optimization.
Optional: Change the lower and upper bounds, base case, or decision variable type for any listed decision variable. Highlight the existing value and type over it. This changes the decision variable definition in your worksheet.
Notice the following about these settings:
The tighter the bounds you specify, the fewer values OptQuest must search to find the optimal solution. However, this efficiency comes at the expense of missing the optimal solution if it lies outside the specified bounds.
By default, OptQuest uses the base case cell values in your Crystal Ball model as the suggested starting solution. If the suggested values lie outside of the specified bounds or do not meet the problem constraints, OptQuest ignores them.
You can sort decision variables in the Decision Variables panel by name, type, freeze status, cell address, worksheet, or workbook. To sort, click the column heading. An arrow is displayed to show the direction of the sort. The sort column and direction of the decision variables is stored as a global preference and is also used to set the order of the decision variables in the reports and extracted data.
When your decision variable selections are complete, click Next.