Detectives, car mechanics and general practitioners all engage successfully in establishing and corroborating findings with little elaborate instrumentation. They often use a modus operandi approach, which consists largely of triangulating independent indices. When the detective amasses fingerprints, hair samples, alibis, eyewitness accounts and the like, a case is being made that presumably fits one suspect far better than others. Diagnosis of engine failure or chest pain follows a similar pattern. All the signs presumably point to the same conclusion. Note the importance of having different kinds of measurement, which provide repeated verification.