Practical Combinatorial Testing
Raghu Kacker, Rick Kuhn, Yu Lei
"Combinatorial methods can help reduce the cost and increase the effectiveness of software testing for many applications.
With the NASA application, for example, 67% of the failures were triggered by only a single parameter value, 93% by 2-way combinations, and 98% by 3-way combinations. The detection rate
curves for the other applications studied are similar, reaching 100% detection with 4 to 6 way interactions."