Running Simulations

The real power of conjoint analysis is the ability to predict preference for product profiles that weren't rated by the subjects. These are referred to as simulation cases. Simulation cases are included as part of the plan, along with the profiles from the orthogonal design and any holdout profiles.

The simplest way to enter simulation cases is from the Data Editor, using the value labels created when you generated the experimental design.

To enter a simulation case in the plan file:

  1. On a new row in the Data Editor window, select a cell and select the desired value from the list (value labels can be displayed by choosing Value Labels from the View menu). Repeat for all of the variables (factors).
  2. Select Simulation for the value of the STATUS_ variable.
  3. Enter an integer value, to be used as an identifier, for the CARD_ variable. Simulation cases should be numbered separately from the other cases.
Figure 1. Carpet-cleaner data including simulation cases
Carpet-cleaner data including simulation cases

For convenience, two simulation cases have been added to the plan file (carpet_plan.sav) for the carpet-cleaner study.

The analysis of the simulation cases is accomplished with the same command syntax used earlier, that is, the syntax in the file conjoint.sps. In fact, if you ran the syntax described earlier, you would have noticed that the output also includes results for the simulation cases, since they are included in carpet_plan.sav.

You can choose to run simulations along with your initial analysis—as done here—or run simulations at any later point simply by including simulation cases in your plan file and rerunning CONJOINT. For more information, see the CONJOINT command in the Command Syntax Reference.

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