The Basis for Constraint tab provides important options when defining a constraint. It determines the subset of the problem, also thought of as the subset of the data, to which the constraint will apply. Depending on the options used, it may lead to creating multiple, or even a large number of, constraints.
For example, you may have a budget constraint that only applies to 3 of the 8 customer segments in the dataset. In that case, the budget upper bound you enter does not apply to the entire problem, but only to the subset of the problem related to those three segments.
The options available are described below.
Based On - This select box one option for each Attribute you have defined for the scenario, as well as the scenario's dimension variable, as in the screenshot below.
Each attribute and the dimension defined in the scenario will be available to use as a basis for the constraint. The exact way it defines the basis is controlled by the additional options described below. When an attribute is selected, the box will re-populate based on that attribute's values in the dataset.
How It's Applied - This selection determine how the constraint is applied by selecting one of four options.
- Combine All Levels into a Single Constraint - every level of the selected variable will be aggregated together to define a single constraint. This is a good option to define a single constraint that should apply to the entire problem.
- Combine Selected Levels into a Single Constraint - When this option is selected, the Which Levels select box is activated. Use this box to select the specific levels of the variable for which this constraint should be applied. All levels selected will be combined together to create a single constraint. Note that this option is not available if there are a large number of levels for the variable.
- Separate Constraint for Each and Every Level - if this option is selected, the constraint will be applied separately for all levels of the selected variable. For example, if the variable is "region" (and say it has 4 levels North, South, East, West in the dataset), and your constraint setup defined budget to be less than $500,000, this selection would create four separate constraints in such a way that the problem will restrict the budget to be under $500,000 separately for each of the four regions.
- Separate Constraint for Each Selected Level - When this option is selected, the Which Levels select box is activated. Use this to select the levels of the variable to which this constraint should apply. The result is the same as the option "Separate Constraint for Each and Every Level ", except that a constraint is created only for the selected levels. Note that this option is not available if there are a large number of levels for the variable.
Which Levels? - This dropdown list will populate with all of the unique values/levels for the variable that was selected, in the case of selecting options involving "selected levels" as described above. Manually check the levels for which this constraint should apply. The list is not available if there are too many levels of the variable to allow for manual selection.