To change the default number of center points
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1    In the Create Response Surface Design dialog box, click Designs.

2    Do one of the following, then click OK.

·    For a central composite design, under Number of center points choose Custom and enter a number in Cube block. When you have more than one block in your design, you also need to enter a number to indicate the number of center points in Axial block.

·    For a Box-Behnken design, under Number of center points choose Custom and enter a number in the box.