The comparisons are improved by switching the stationary pairs according to a matrix as follows. The highest numbered pair usually remains stationary, while one line from the matrix is selected for each other stationary pair. The lines of least switches are normally chosen for convenience. It should be noted that this matrix is set up for 16 rounds. The matrix is complete for that number, but it can be truncated at any point up to that number.
This matrix can also be used in Butler or Barometer events where all the boards up to 16 are played per round. 8 rows are selected to give the switching of the boards for the 8 tables. In fact if rows 1, 3, 4, 7, 8, 9, 13 and 14 are selected, then all pairs have equal dealer vulnerability opportunities using a standard set of boards. N-S direction is shown by + and E-W as -.
1. + + + + + + + + + + + + + + + +
2. + - + - + - + - + - + - + - + -
3. + + - - + + - - + + - - + + - -
4. + - - + + - - + + - - + + - - +
5. + + + + - - - - + + + + - - - -
6. + - + - - + - + + - + - - + - +
7. + + - - - - + + + + - - - - + +
8. + - - + - + + - + - - + - + + -
9. + + + + + + + + - - - - - - - -
10. + - + - + - + - - + - + - + - +
11. + + - - + + - - - - + + - - + +
12. + - - + + - - + - + + - - + + -
13. + + + + - - - - - - - - + + + +
14. + - + - - + - + - + - + + - + -
15. + + - - - - + + - - + + + + - -
16. + - - + - + + - - + + - + - - +
