VALIDATION, makes sure that your data is sensible and helps to reduce the number of errors when on the computer.
There are different types of validation
Types of validation
Type Check - If you only want numbers to be entered. (E.G if you are writing the quantity of items you are selling in a shop)
Range Check- When you want to make sure that the data typed is within a range.( E.G. if you only want people over 18 to buy alcohol .. >=18 )
Presence Check - When you want to make it compulsory that certain data is entered.(E.G if you want to make sure someone fills in their age on a form)
Picture of Format Check - When you want to make sure that numbers and letters are in the right format. (E.G a postcode)
Check didgit - when you want to check a range of numbers have been entered correctly (E,G a barcode with a certain number at the end)
Checks that the data you have entered against the original source. This is to make as few mistakes as possible.
There are three ways to do this
Entering the data twice
You enter the data twice so that the computer can check that the two sets of data match.
An example is when you are registering for a website and they make you type in the password twice.
Its time consuming for large amounts of data
You could enter a wrong piece of data twice
Checking against a hard copy
This is when you manually check the computer screen against a hard copy of the data, looking for mistakes.
Very time consuming
Difficult to move eyes between large amounts of data on the screen and on paper.
Comparing two hard copies
Print out a copy of the new data and check it against the original copy. This is similar to checking against a computer screen but may be easier and they can be put close together and compared.
Easy to miss mistakes