Plackett-Burman Factor Information

Factors: How many two-level factors will be in the experiment?


Plackett-Burman designs are built with multiples of four runs (N = 4, 8, 12, 16, 20, …) and handle exactly N-1 factors. If there are fewer than N-1 factors in the experiment be sure to rename the factors at the bottom with Dummy before each letter. Dummy variables create place holders for the columns required to build a Plackett-Burman design. If a Dummy variable comes up significant during the analysis then interactions are being confounded with the main effects. A fold-over will be required to de-alias the main effects.

Name: (defaults to alphabetically ascending letters) Enter a descriptive name for each factor.

Units: (optional) Enter the units of measure for each factor.


Numeric Factors: Defines a range for the factor settings. Any value between the low and high level is available for the experiment. Numeric factors allow center points to be added to the design.

Categoric Factors: This type of factor is one that simply uses names or classes to describe the levels. For instance, peanut butter types (Creamy vs. Chunky).

Low: For a numeric type, the minimum setting for the factor. For categoric type, the arbitrary low setting.

High: For a numeric type, the maximum setting for the factor. For categoric type, the arbitrary high setting.

Center Points: (bottom) Enter the number of center points for detecting curvature.