In essence, reliability is the consistency of test results. To understand the meaning of reliability and how it relates to validity, imagine going to an airport to take flight #007 from Pittsburgh to San Diego. If, every time the airplane makes the flight, the passengers are dropped off in Dallas, Flight #007 is not making it to its target destination. Therefore, it is not a valid claim for the airlines to advertise that flight #007 takes passengers from Pittsburgh to San Diego. If flight #007 goes from Pittsburgh to Dallas consistently, however, the flight is reliable, even though it takes passengers to the wrong destination. As with an airline flight destination, the level of reliability affects the level of validity in educational testing, which will be addressed throughout this chapter.