Validation and verification

Validation is the checking of data as it's being input to make sure it conforms to certain rules. This reduces the number of data entry errors, but it doesn't ensure that the data is correct, only that it's in an acceptable format. It has some methods:

- Range check: tha data must be between limits.
- Type check: the data must be correct data type
- Presence check: a mandatory field
- Check digit: a calculation produces an extra digit-the digit must match when the data is input. Bar codes have check digits.
- Existence check: the data must match some pre-existing data item, for example, an account number taht exists. Drop-down boxes can look up allowable data in a list.


Verification means making sure that data is correct. The data may be compared wuth the source or sometimes two people type in the same data and the computer checks taht the data is the same.





http://en.wikipedia.org/wiki/Verification_and_validation
http://softwaretestingfundamentals.com/verification-vs-validation/
http://www.asmeconferences.org/vvs2013/