Draper and Mitchell (1970) gave an example which showed that two 2k-p designs with the same word length pattern can be different. The difference was detected via a 'letter pattern comparison' test. These authors went on to conjecture that two designs with equivalent letter pattern matrices are indeed equivalent designs. We show this conjecture is not true by giving an example of two different designs with identical letter pattern matrices. Thus, more effort is needed to construct a complete set of 2k-p designs.
All Science Journal Classification (ASJC) codes
- Statistics and Probability
- Statistics, Probability and Uncertainty
- Applied Mathematics