Validation and Verification

When do errors occur?

transcription

Typing in errors

Input

reduced by human involvement

Processing

programming errors,
incorrect formulae,
processing wrong data.

Transmission

Detect errors and re-send, Parity checks.

Verification is when individuals check the data.

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.

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.

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.

Validation is performed by a computer programme.

Types of validation check.

length

Checking that the data is the correct number of digits long.

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.

Cross field

Range

Presence

checking that something has been written down.

Format

Data Type

Checking that data follows the correct rule, for example, a telephone must be numbers only and not letters

What the computer checks for

Checks that the data is reasonable

Uses rules/formulas

However it cannot eliminate all errors

Checks the data is sensible