Content deleted Content added
mNo edit summary |
|||
Line 1:
{{orphan|date=November 2009}}
'''Two pass verification''', also called '''double data entry''', is a data entry quality control method that was originally employed when data records were entered onto sequential 80 column [[Hollerith card]]s with a [[keypunch]]. In the first pass through a set of records, the data keystrokes were entered onto each card as the data entry operator typed them. On the second pass through the batch, an operator at a separate machine, called a ''verifier,'' entered the same data. The verifier compared the second operator's keystrokes with the contents of the original card. If there were no differences, a verification notch was punched on the right edge of the card. [http://www.museumwaalsdorp.nl/computer/en/punchcards.html]
Line 6 ⟶ 8:
While this method of quality control clearly is not proof against systematic errors or operator misread entries from a source document, it is very useful in catching and correcting random miskeyed strokes which occur even with experienced data entry operators. However, it proved to be a fatally tragic flaw in the [[Therac 25]] incident. This method has survived the keypunch and is available in some currently available data entry programs (e.g. [[PSPP]]/[[SPSS]] Data Entry). At least one study suggests that single pass data entry with range checks and skip rules approaches the reliability of two-pass data entry (see Controlled Clinical Trials from sometime in the 1990s - Control Clin Trials. 1998 Feb;19(1):15-24.?); however it is desirable to implement both systems in a data entry application.
{{DEFAULTSORT:Two Pass Verification}}
[[Category:Data collection]]
[[Category:History of computing]]
| |||