Design of a Robust Design Experiment - Alias Structure Tab

Click the Alias structure button to display a spreadsheet showing a matrix of main effects (rows) by two-way interaction effects (columns). If the entries in the matrix are blank, then the respective two effects (main effect and interaction effect) are not confounded with each other (they are orthogonal). Asterisks (*) in this matrix mark effects that are not orthogonal.

This option is useful for identifying whether or not certain two-way interactions are confounded with the main effects in the design, and, if so, with which ones. Some orthogonal arrays allow you to estimate some two-way interactions, provided that specific main effects are not used (i.e., that those columns in the design are not used). Please refer to Phadke (1989) or Taguchi (1987) to learn more about advanced methods of "manipulating" and "molding" orthogonal arrays to accommodate specific unusual design needs (via the use of linear graphs).