Validation and Verification
Validation is performed by a computer programme.
What the computer checks for
Checks the data is sensible
However it cannot eliminate all errors
Uses rules/formulas
Checks that the data is reasonable
Types of validation check.
Data Type
Checking that data follows the correct rule, for example, a telephone must be numbers only and not letters
Format
Presence
checking that something has been written down.
Range
Cross field
File/table look-up
This is when we see a drop-down-box with a variety of options to make, this makes the information easier for the computer to process becasue there is a limit on the answers.
length
Checking that the data is the correct number of digits long.
Verification is when individuals check the data.
Sending back printouts
This is when we ask a customer to check the data they have given to us has been typed/written down correctly, any errors can then be pointed out and fixed.
Double entry of data
This is when a piece of data is typed in twice, if the two pices match they are accepted, this is usually seen on websites asking for a password or an e-mail address.
Proof reading
This is carefully reading what has been typed in and comparing it with whats on the data source (eg, order forms, invoices, surveys.) for any errors, so they can be corrected.
When do errors occur?
Transmission
Detect errors and re-send, Parity checks.
Processing
programming errors,
incorrect formulae,
processing wrong data.
Input
reduced by human involvement
transcription
Typing in errors
