Using Excel to program a decision tree model is a moderate easy task. Using Excel provides the advantage of using equations and formulas to make the calculations and reduce any potential error. Although drawing a branch of a tree may take some time, using the Copy-Paste function of Excel may be practical to create the additional tree branches. Basic tools to draw the trees include (see Figure 10.8):

1. Borders tool (to draw the branches)
2.  Insert shapes function (to draw nodes in the tree)
3. Merge and center tool (to produce consistent format)
4. Developer tools (adding additional functionality)

Figure 10.8 Excel tools to draw decision trees.

Building a decision tree in Excel is easier if first we give some thinking to the problem and sketch the tree in advance in a piece of paper. It is easier to draw the tree from right to left. Drawing a tree in Excel involves three basic tasks:

• Adding horizontal borders to a merged group of cells
• Adding diagonal borders to a merged group of cells (to see the diagonal border you will need to choose the option “More Borders”
• Combine diagonals, horizontals and shapes to produce decision or chance nodes

Figure 10.9 includes a tree model for the warming up exercise using Excel equations to make calculations.

Figure 10.9 Tree model in Excel

Attribution

By Luis F. Luna-Reyes, Erika Martin and Mikhail Ivonchyk, and licensed under  CC BY-NC-SA 4.0.