Optimal Design Result: Response Surface - Display Design Tab

Select the Display design tab of the Optimal Design Result: Response Surface dialog box to access options to specify the appearance of the design, review the design, and change any factor names or levels.

Display design

Click the Display design button to produce a spreadsheet containing the selected points. The way in which these points are displayed is affected by the settings of the options on this tab. To save the design, select the spreadsheet and use the Save or Save As options on the File menu.

The second column of the spreadsheet contains the prediction variances. For design point i, this value is computed as (see Mitchell, 1974b):

si2 = f(xi)'*(X'X)-1*f(xi)

where X stands for the design matrix, and f(xi) is the vector of codes associated with the factor effects in the current model for design point i.

Denote factors

The option selected in the Denote factors group box determines how the factors are labeled in the spreadsheet. See the note on denoting factors for more details.

By numbers

If you select the By numbers option button, the factors will be denoted by numbers; that is, consecutive factors will be labeled as F1, F2, ..., Fn.

By letters

If you select the By letters option button, the factors will be denoted by letters; that is, consecutive factors will be labeled as A, B, C and so on.

By names

If you select the By names option button, the factors will be denoted by their names as entered on the input spreadsheet.

Order of runs

The option selected in the Order of runs group box affects the order of runs displayed in the spreadsheet (via option Display design, see above).

Standard order

Select the Standard order option button to display the design in standard order (the order in which it appears in the candidate list).

Random

To randomize the order of runs, select the Random option button. For standard experiments, it is common practice to randomize the runs in order to avoid any systematic biases due to fluctuations in the production process across runs.

Seed

The positive integer value in the Seed box is used to seed the random number generator. Note that the random number generator will be reseeded, every time you enter this dialog. Thus, when you generate the same design more than once, the default random seed in the Seed box is different every time.