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While Validation ensures that data adheres to business rules and reasonable limits, it cannot guarantee that the entered data is factually identical to the source document. That critical task is fulfilled by Verification.
1. Definition of Verification
Verification is the process of checking that data has been transferred or copied accurately from an original source document to a computer system without introducing transcription errors (mistyped keys or omitted characters).
2. The Two Primary Verification Methods
1. Double Entry
- Mechanism: Data is entered into the system twice—either by two different operators working independently, or by the same user entering the data twice (such as entering and re-confirming a new password or email address).
- Processing: The computer program automatically compares both entries character-by-character.
- Outcome: If the two entries match identically, the data is saved. If any discrepancy exists, the user is alerted to re-enter the data.
- Advantage: Highly effective at catching inadvertent keystroke errors.
2. Visual Check (Screen Proofreading)
- Mechanism: The user manually proofreads the data displayed on the screen against the original paper source document before confirming submission.
- Limitation: Highly prone to human cognitive fatigue and oversight, especially during repetitive, high-volume data entry.
3. Comprehensive Comparison: Validation vs Verification
Dimension | Validation | Verification |
|---|---|---|
Core Question | "Is this data sensible, reasonable, and allowable according to the rules?" | "Is this data an exact, faithful copy of the original source document?" |
How Carried Out | 100% automated by program software routines. | Program comparison (Double Entry) or human inspection (Visual Check). |
Detection Scope | Catches out-of-range numbers, wrong lengths, missing values, incorrect formats. | Catches keystroke mistakes and transcription discrepancies. |
Failure Scenario 1 | Source says Age: 14. Typist enters 41. Passes verification if typed 41 twice, but fails a range check ($11 \le \text{Age} \le 18$). | |
Failure Scenario 2 | Source says Exam Mark: 78. Typist enters 87. Passes range check ($0 \le \text{Mark} \le 100$), but fails verification because $87 \ne 78$. |
Written practice and self-review
A clerk enters customer orders from paper order forms into a computer system using double entry verification. Explain why double entry verification cannot detect an incorrect price if the price was written incorrectly on the original paper order form.
Write an explanation before checking the theory. Check that each claim answers the question, uses the correct concept and explains why it applies. Discuss uncertain points with a teacher. The structured exercise below checks specific facts; it does not automatically mark this explanation.
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Application: Check the reasoning
Application: Check the reasoning
- Compare two independently entered copies: [Space 1]
- Compare entry against the original document: [Space 2]
- Does matching double entry prove both entries are true: yes or no? [Space 3]
Interactive exercises for Module 2 and beyond require an active plan.