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Several studies indicate that the vast majority of defects (67%-84%) related to input values are due to either to a problem in a parameter value (single-value fault) or in a combination of two parameter values (2-way interaction fault).

Single-value faults are mostly probable to typical mistakes, such as the off-by-one bug (e.g., imagine using a loop and using the < operator instead of <=). The interaction of 2 parameters may be to bugs around implementing cascade conditional logic statements (e.g. using if or similar) involving those parameters/variables.

Bugs related to the interaction of more parameters decrease with the number of parameters; in other words, find these rare bugs will require much more tests to be performed, leading to more time/costs.

Pairwise and n-wise Testing

Given the empyrical data, adopting pairwise testing to test all the ombinations of pairs of parameters (sometimes also called as "all pairs testing") is a technique that is feasible.

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