User chooses number of runs. The custom designer starts with a random design with each point inside the range of each factor. The computational method is an iterative algorithm called coordinate exchange . Each iteration of the algorithm involves testing every value of every factor in the design to determine if replacing that value increases the optimality criterion. If so, the new value replaces the old.
Iteration continues until no replacement occurs in an entire iterate.
To avoid converging to a local optimum, the whole process is repeated several times using a different random start. The designer displays the best of these designs. Sometimes a design problem can have several equivalent solutions. Equivalent solutions are designs with equal precision for estimating the model coefficients as a group. All rights reserved.