Garbage In, Garbage Out

gigo

Garbage in, garbage out (GIGO) in the field of computer science or information and communications technology refers to the fact that computers, since they operate by logical processes, will unquestioningly process unintended, even nonsensical, input data (‘garbage in’) and produce undesired, often nonsensical, output (‘garbage out’). The principle applies to other fields as well.

The underlying principle was noted by the inventor of the first programmable computing device design: ‘On two occasions I have been asked, ‘Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’ … I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.’

It was popular in the early days of computing, but applies even more today, when powerful computers can produce large amounts of erroneous information in a short time. The first use of the term has been dated to a 1963 syndicated newspaper article about the first stages of computerization of the IRS. The term was brought to prominence as a teaching mantra by George Fuechsel, an IBM technician. Early programmers were required to test virtually each program step and cautioned not to expect that the resulting program would ‘do the right thing’ when given imperfect input.

The term can also be used as an explanation for the poor quality of a digitized audio or video file. Although digitizing can be the first step in cleaning up a signal, it does not, by itself, improve the quality. Defects in the original analog signal will be faithfully recorded, but may be identified and removed by a subsequent step (e.g. digital signal processing). In statistics the concept is conveyed by the maxim: ‘It is not possible to carry out an accurate statistical analysis of inaccurate data.’

‘Garbage in, gospel out’ is a more recent expansion of the acronym. It is a sardonic comment on the tendency to put excessive trust in ‘computerized’ data, and on the propensity for individuals to blindly accept what the computer says. Since the data entered into the computer is then processed by the computer, people who do not understand the processes in question, tend to believe the data they see. This has serious implications as decision-makers increasingly face computer-generated information and analyses that could be collected and understood in no other way.

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