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Performing Spreadsheet What-If Analysis 36
Types of What-If Analyses
Not surprisingly, Excel can handle much more sophisticated models than the preceding example. To perform
a what-if analysis using Excel, you have three basic options:
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Manual what-if analysis: Plug in new values and observe the effects on formula cells.
Data tables: Create a table that displays the results of selected formula cells as you systematically
change one or two input cells.
Scenario Manager: Create named scenarios and generate reports that use outlines or pivot tables.
Manual What-If Analysis
This method doesn’t require too much explanation. In fact, the example that opens this chapter demonstrates
how it’s done. Manual what-if analysis is based on the idea that you have one or more input cells that
affect one or more key formula cells. You change the value in the input cells and see what happens to the
formula cells. You may want to print the results or save each scenario to a new workbook. The term scenario
refers to a specific set of values in one or more input cells.
Manual what-if analysis is very common, and people often use this technique without even realizing that
they’re doing a type of what-if analysis. This method of performing what-if analysis certainly has nothing
wrong with it, but you should be aware of some other techniques.
TIP
If your input cells are not located near the formula cells, consider using a Watch Window to
monitor the formula results in a movable window. Chapter 4 discusses this feature.
Creating Data Tables
This section discusses one of Excel’s most underutilized features: data tables. A data table is a dynamic range
that summarizes formula cells for varying input cells. You can create a data table fairly easily, but data tables
have some limitations. In particular, a data table can deal with only one or two input cells at a time. This
limitation becomes clear as you view the examples.
NOTE
Scenario Manager, discussed later in this chapter (see “Using Scenario Manager”), can produce
a report that summarizes any number of input cells and result cells.
Don’t confuse a data table with a standard table (which is created by choosing Insert ➪ Tables ➪ Table).
These two features are completely independent of each other.
Creating a one-input data table
A one-input data table displays the results of one or more formulas for various values of a single input cell.
Figure 36.2 shows the general layout for a one-input data table.
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