Validation and verification compared

Overview

Data validation, data verification and why validation cannot guarantee that data is accurate.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is meant by data validation?

   Model answer

   Validation is an automatic check that data entered is sensible and of the expected form. A validation check cannot prove that the data is actually correct.

2. 2

   What is meant by data verification?

   Model answer

   Verification is a check that data has been copied or transferred accurately from its source. The value itself may still be wrong on the original document.

3. 3

   Explain why validation cannot guarantee that data is accurate.

   Model answer

   Validation only tests whether a value obeys a rule such as lying inside a range. A wrong date of birth inside the allowed range passes every check.

4. 4

   A user types a surname into a field that expects a date. Which kind of check rejects the entry?

   Model answer

   A type check rejects the entry because letters are not a valid date value. The rejection happens before the data is written to the file.

5. 5

   Give one situation where verification matters more than validation.

   Model answer

   Verification matters most when data is re-keyed from paper forms into a computer system. A typing slip produces a plausible value that passes every validation rule.

6. 6

   Why are validation and verification normally used together?

   Model answer

   Validation traps values of the wrong form and verification traps values copied wrongly. Neither check on its own removes both classes of error.

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