A Note on the Output of a Coordinate-Exchange Algorithm for Optimal Experimental Design

Abstract

The coordinate-exchange algorithm is commonly used to construct optimal experimental designs. Every execution of the coordinate-exchange algorithm produces a new, seemingly random, order of the selected design points. In this short communication, we study the order of the design points produced by the algorithm and conclude that certain orders appear much more often than others. As a result, an explicit randomization step of the design points is required before conducting an experiment using a design produced by a coordinate-exchange algorithm.

Figures (2)

• Figure 1: Single execution of the coordinate-exchange algorithm
• Figure 2: Frequency distribution of the 720 different orders of the six D-optimal factor level combinations.