Configuring the Factors

You can use the Factors tab to select the parameters that you want to use as factors to study in a Design of Experiments analysis type.

  1. Double-click the Six Sigma component icon .

    The Six Sigma Component Editor appears.

  2. From the Six Sigma Component Editor, click the Factors tab.

    The tab presents a table of available input parameters to select as factors to study, along with columns for attributes to specify for each factor. The attributes to specify are determined by the DOE technique being used.

  3. Right-click in the table to access various options for working with factors.

    For more information, see Setting Table Options.

  4. Determine which parameters you want to use as constraints by selecting the corresponding check boxes in the first column. Alternatively, you can click Check to select all the selected parameters as constraints. To clear all the parameters, click Uncheck.

    To select aggregates, click and select the scalar members.

    Tip: You can also right-click on the aggregate, and select Expand all.

  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 set of attributes are common among many of the techniques:

    Option Description
    # 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”. This attribute is set to the current parameter value by default.
    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.
    Alpha (Central Composite 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 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 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.

  6. Click Update factor baselines to current values when executing if you want the baseline values updated to the current parameter values before executing.

    If Isight previously modified a parameter, this option allows for automatic updating of the baseline of all factors to the current parameter values in Isight, prior to executing the DOE technique, which will readjust the values to be studied appropriately. The default is to have this option not selected, retaining user-defined settings. This option is useful if the DOE technique is executed after another element of the simulation process flow that might change the parameter values (e.g., after an Optimization component), so that the DOE study can be performed around the new design point.

    Note: If the Six Sigma component is driven by an Optimization component to perform robust optimization (Six Sigma Optimization run mode is selected), this option is not available. Factor baselines will update automatically for parameters that are also design variables.

  7. If desired, click Edit to set factor attributes for one or multiple factors.

    For more information, see Editing Attributes for Multiple Parameters.

  8. Click OK to save your changes and to close the Six Sigma Component Editor.