1. Create a central composite design for two factors using SAS ADX or data step commands.

(a) Create the uniform precision CCD and store the design along with ran-

dom numbers (simulated response) in a SAS le.

(b) Create a ne grid of points over the unit square and augment your CCD design with this grid (leaving the simulated response variable as missing values).

(c) Use proc reg to t the general quadratic model and output the standard errors of the predicted value over the unit square.

(d) Make a contour plot of the standard errors of the predicted values over the unit square.

(e) Repeat

(a) through

(d) for a face-centered cube design (i.e., CCD with axial points at 1).

(f) Based on the contour plots you made, which design do you prefer? State the reason.