11. Verification

It was mentioned earlier that validation cannot make sure data that you enter is correct, it can only check that it is sensible, reasonable and allowable.

However, it is important that the data in your database is as accurate as possible.

Verification can be used to help make sure that the data in your database contains as few mistakes as possible.

Verification can be performed in a few ways:

Entering the data twice.

Think about when you choose a new password, you often have to type it in twice. This lets the computer check if you have typed it exactly the same both times and not made a mistake.  It verifies that the first version is correct by matching it against the second version.
Whilst this can help to identify many mistakes, it is not ideal for large amounts of data. 

• It would could take a person a lot of time to enter the data twice.
• They could enter the same mistake twice and so it wouldn't get picked up. 
• You would end up with two copies of the data.

Checking the data on the screen against the original paper document

This saves having to enter the data twice.  It can help pick up errors where data has been entered incorrectly or transposed. 

However, it isn’t always that easy to keep moving your eyes back and forth between a monitor and a paper copy. Also, if you are tired or your eyes feel 'blurry' then you might miss errors.

Printing out a copy of the data and comparing the printout to the original paper document.

This is probably the easiest of the verification methods because you can have both copies side by side and scan both for mistakes.
However, it can be time consuming if there is a large amount of data to check and if you do it too quickly, mistakes could be overlooked.

Getting a helping hand

If you work with colleagues, than a good way of reducing errors is for another person to read your data entries whilst you call out from the original list. This can take up a lot of time though and it ties up two people, so it depends on how critical the data is. Note that it is better for the second person to read the data entries rather than yourself, because often you can make the same mistake twice such as transposing a number.