Roll Back Settings

DTace Tutorials > Tree Settings > Roll Back Settings

The Roll Back page of the settings form is used to set number of digits, utility function R values, and to set-up a custom utility function.

Display Value

This setting is used to show what value to show on the tree.  There are four possible values.

  • Expected monetary value
  • Exponential utility
  • Certainty equivalent
  • Custom function

Depending on the value selected, different setting fields will appear or be hidden.  If exponential utility or certainty equivalent is selected, a box will appear to enter the risk tolerance constant, R.

Maximum Decimal Places

For each data type, select the maximum number of decimal places to display on the tree.

The Roll Back page is shown below with expected monetary value selected.

The Roll Back page is shown below with exponential utility value selected.  Note that same fields will be shown if certainty equivalent is selected.

The Roll Back page is shown below with custom function value selected.

Custom Function

If custom function is selected in display value, then the custom function pane will appear as shown above.  There are two cells that must be referenced: one cell for the software to plug in the terminal payoff and one cell to calculate the utility.

The example shown below shows a custom utility function in cell AL10.  Terminal payoff for each end node is inserted into cell AL9 and the utility function in cell AL10 uses the value in AL9 to calculate utility.  The calculated utility in AL10 is then inserted back into the node's terminal utility.  The cell references for this set-up are shown in the roll back settings above.