One system (A) was having failures that occurred every hour, while another system (B) was experiencing no problems. It was thought that a combination of two things might be causing a problem to occur....

One system (A) was having failures that occurred every hour, while another system (B) was experiencing no problems. It was thought that a combination of two things might be causing a problem to occur. A big picture was needed for the investigation because many one-at-a-time changes gave no indication of the origin of the problem. A brainstorming session yielded the following six possible causal factors: hard file hardware, processor card (a difference between component tolerances could affect a critical clock speed), network interface card, system software (was thought to be the same but there might be some unknown internal setup differences), a software internal address of the system, and the remaining components of the system hardware.

(a) Design a two-level test such that 100% of all two-factor level combinations would be evaluated.

(b) Determine the test coverage for three-factor combinations and four factor combinations.