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Data Verification
Typing data into a computer from a data capture form is called transcribing.
If an error is made it is a transcription error.
Human typists are poor devices - they frequently make mistakes, so we
need...
Verification is
carried out to check that data is transcribed correctly.
Methods of verification...
| Screen verification |
A visual check by eye that no errors have been made.
This is sometimes done by printing out data that has been
input, and sending it back to the source of the data to check.
Example: printed proofs of the pages of a book may be sent
back to the author for checking (proof-reading). |
| Double-keying |
This is a check to see if data has been keyed
in correctly.
The data is keyed in twice
(usually by two different people), and the computer will only accept the data for processing if the two
versions are identical.
Example: Creating a new
password.
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| Check digit |
For numerical data. A check digit is an extra digit added on to a
number. This check digit is the result of a calculation performed on the digits of the
number.
When the data is entered into the computer, it performs the
same calculation to see if the check digit is correct...ie it checks the check digit!
Examples
The last digit of a bar code is a check digit.
The last digit of an ISBN number on a book is a check digit.
Incidentally...this is one reason why you cannot 'invent'
credit card numbers!
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