Configuring the Factors

You can select and configure the input parameters that you want to use as factors to study. The attributes that you can configure are determined by the DOE technique you selected.

See Also
Mapping Options and Attributes to Parameters
  1. From the Flow section of the action bar, click DOE and drop it on the process diagram.
  2. Double-click DOE .
    The DOE Editor appears.
  3. From the DOE Editor, click the Factors tab.
  4. Determine which parameters you want to define as factors to study by selecting the corresponding check boxes in the first column.
  5. Change any of the default values, which are provided for all attributes for a selected factor.

    Depending on the technique, a change in one of the columns might automatically update any other columns that are related.

    Although each technique defines the appropriate set of attributes for a factor, the following attributes are common among many of the techniques:

    • # Levels. The number of levels at which you want to study the factors. A change to this attribute automatically readjusts the levels for this factor.

    • Levels. A space-separated list of the levels at which to study the factor. The related attributes are updated once you click in a different cell.

    • Lower/Upper. The lower/upper levels for the factor. A change to one of these attributes automatically calculates new levels evenly distributed between the lower and upper values.

    • Relation. Specifies whether the levels are interpreted as values or as %/difference (diff) from a specified baseline.

    • Baseline. The value used for converting levels into values when the relation is % or diff.

    • Values. A space-separated list of the actual values at which to study the factor. The Values are calculated using the Levels (or Lower/Upper values) as a percentage or difference (specified by the Relation attribute) from the Baseline (for techniques that support those attributes).

      For example, for Levels = “-10 10”, Baseline = 20, Relation = “%”, the Values are calculated as “18.0 22.0”.

      Because the values are calculated from other attributes, you cannot edit the contents of this column.

    The following attributes are not common to all the techniques:

    • Alpha (Central Composite technique only). The lower and upper levels specify the two levels at which a 2-level full-factorial study is performed. The center point is also studied. The Alpha option is a ratio defining two other points (also known as “star points”) at which to study the given factor. For example, Alpha set to 0.25 indicates that the factor is to be studied at points 1/4 of the way from the baseline to the lower and upper levels. Alpha set to 1.5 indicates that the factor is to be studied 50% beyond the lower and upper levels. For example, Lower = 5, Upper = 20, Baseline = 10, and Alpha = 0.25 results in Levels = {5, 8.75, 10, 12.5, 20}.

    • Column (Data File only). If you specified to not use a header row to find factors in the file, you must provide the column number for each factor.

    • Step Size (Adaptive DOE technique only). This value is the spacing between the potential sample points within the given bounds. The step size for real parameters must be any positive real value; the value for integer parameters must be any positive integer value. If you do not specify the Step Size for real parameters, the step size is the value of the tuning parameter Significant Step Size times the span of the bounds; if you do not specify the Step Size for integer parameters, the step size is 1.

    • Allowed Values (Adaptive DOE technique Sobol Sequences technique). This option is required for boolean and string Factors, but optional for real or integer factors. Type a list of allowed values in the Allowed Values column, separated by a semicolon. If you enter allowed values, a step size value is not required. Entering a list of allowed values creates a discrete variable, and the DOE adapter uses only these values.

  6. Optional: Click Update baselines to current values when executing if you want the baseline values updated to the current parameter values before running.
    If Optimization Process Composer previously modified a parameter, this option allows for automatic updating of the baseline of all factors to the current parameter values in Optimization Process Composer, before running the DOE technique, which will readjust the values to be studied appropriately. By default, this option is not selected and the user-defined settings are retained. This option is useful if the DOE technique runs after another element of the simulation process that might change the parameter values (for example, after an Optimization adapter), so that the DOE study can be performed around the new design point.
  7. Optional: Map an option to a parameter.
  8. Click Ok to save your changes and to close the DOE Editor.