The most common challenge faced in testing community is to ensure for optimum test coverage. However, it is very difficult to test all possible permutation and combinations; many a times the tester assumes that test coverage is been established by review processes and timely feedback. One common school of thought in improving test effectiveness is through automation, but automating the entire test suite (with all combinations) involves significant testing cost and time. Six sigma framework gives a tangible solution for this pain area based on a mathematical approach / model i.e. Orthogonal array technique ( deduced from Design of experiments model ). The success of this approach is that it establishes an optimal blend between Test coverage, Cost.