Which one of the following statements is incorrect?

Explanation

Deriving test cases from the specification or the requirements, without any knowledge of the internal code, is the definition of black-box testing; white-box (structural) testing derives its test cases from the program's internal logic, control flow and data flow. So statement 4 is the incorrect one. The other three are all true: Pareto analysis is the 80–20 statistical technique used in software quality assurance to find the few causes responsible for most defects, reliability is formally the probability of failure-free operation over a stated period in a stated environment, and MTTF is one of the accepted quantitative reliability measures. Hence the answer is the white-box testing statement.