The test fuel matrix provided in the regulations delineates the minimum test program that would be acceptable to the Agency for Complex Model augmentation. A more comprehensive test program, which would provide the full set of orthogonal matrices which is statistically necessary, is allowed and is encouraged. The Agency expects that primary interactive effects can be adequately identified with the required minimum test fuel matrix.(7/1/94)

This question and answer was posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)