Verification

Your text books often underestimate the importance of verification. In its simplest form an end user types in some simple data - like a password. The user is then asked to type it in again. The computer "verifies" one copy against the other.

When data is transcribed from one medium to another there is always a danger that errors will be introduced. The copy will not then be the same as the original. This is particularly true if the transcription is being done manually as when a human operator reads a source document and uses a keyboard to transcribe the data to a computer readable format (key to disc or key to tape systems).

Verification is designed to trap a transcription error. If data has been copied automatically from one format to another then verification will consist of the computer system reading the copy and checking it against the original. So for example a text file may been transmitted via a radio link twice then the two copies checked against each other for differences.

If a keyboard operator has done the transcription then this type of check is impossible. In this situation the data is re-entered by a different operator with the computer system checking for differences as the second copy is entered. Any differences must be the result of a transcription error by one of the two operators. In this case the transcribed versions can be checked manually against the source document and the error corrected.

Whilst verification reduces errors it does not eliminate them. If a typist thinks "Great" is spelled "Grate" they will retype the error.

© LEV