The Metrics outline gives you information about how well the design meets the strength requirements. See Dalal and Mallows (1998) for background on these metrics for unconstrained designs.
t
The number of factors.
Coverage
The ratio of the number of distinct t-factor settings that appear in the design to the total possible number of t-factor settings, expressed as a percentage. A t-coverage of 100% indicates that all possible t-factor settings are covered by the design. Note that each t-factor setting can appear multiple times.
For constrained and unsatisfiable designs, the definition of Coverage is adjusted for the number of t-factor settings that are possible once the constraints have been applied to all t-factor combinations. See Formulas for Metrics.
Diversity
The ratio of the number of distinct t-factor settings in the design to the total number of occurrences of t-factor settings in the design, expressed as a percentage. The t-diversity measures how well the design avoids replication. A t-diversity of 100% indicates that no t-factor settings are repeated. A t-diversity of 50% indicates that the average number of times that distinct t-factor settings appear is two.
For constrained and unsatisfiable designs, the definition of Diversity is adjusted for the number of runs with missing settings. See Formulas for Metrics.