Validation
A check that is performed by the computer as the data is being entered. It tries to prevent entry of any data that does not conform to pre-set rules.Validation does not stop incorrect data from being entered, however it does ensure that data is: Sensible, reasonable, within acceptable boundaries and complete.
Checks that can be applied fall into several categories: Range, type, presence, length, lookup, picture and check digit.
Checks that can be applied fall into several categories: Range, type, presence, length, lookup, picture and check digit.
Range Checks
Sets an upper and lower boundary for the data, data entered must lie between these two boundaries.
E.g. Years 7-13
E.g. Years 7-13
Type Checks
Make ssure that all data entered is the correct type, including numeric, string, boolean, and date/time. Type checks will not allow you to enter the wrong type of data.
E.g. Word entered into a numeric field it will be rejected.
E.g. Word entered into a numeric field it will be rejected.
Length Check
Any data entered into a computer it has a length, length ensures that the data cannot be more than a set number of charecters.
Lookup Checks
Where data is cross referenced against a list to make sure that it is valid and acceptable. Cross referencing may give additional information. Lookup validation is not a search, it is a comparison against known data.
Picture Checks
Also known as a format check, some data enteries might be a combination of numbers and letters, therefore you cannot apply a type check.
Check Digit
Check digit is calculated using a set of numbers and then added to the end of them. When the code is created, the check digit is created and added to the code. Before the code is then processed, the check digit is recalculated and compaired with the one in the code.If they are the same, processing continues. If they are not, an error has occured and the code value needs to be re-entered.
Verification
Data collected from a form, will eventually need to be entered into a computer, giving you two copies, paper-based and digital. The paper-based is known as source document and digital copy, object document. Verification is making sure that the information on the source document is the same as the object document.
Two main methods of verification: double entry and manual verification.
Two main methods of verification: double entry and manual verification.
Double entry
Entering the data twice, the computer compares the two sets of data and differences are informed to the user to make the appropriate changes. Password are one method of double entry that you will come across.
Main problem with double entry is that if the same error is made both timesthen the computer will not find a difference.
Main problem with double entry is that if the same error is made both timesthen the computer will not find a difference.
Manual Entry
Manual verification is essentially proofreading the data. Involves compairing the source data with the entry typed into the computer. It relies on the person being able to follow two sets of data. It is not very reliable, as it is difficult to transfer attention between screen and paper.
Common errors
Two most common errors are caused when entering data into a computer are transcription and transposition errors.
Transcription errors - Mistake made when copying the data. E.g. Spelling Error
Transposition errors - Mistake of swapping two letters in a word. E.g. Brian and Brain
Transcription errors - Mistake made when copying the data. E.g. Spelling Error
Transposition errors - Mistake of swapping two letters in a word. E.g. Brian and Brain
Degree of Accuracy
Neither validation nor verification can ensure that the data has been entered is accurate. It is still possible to enter data that meets the validation rules but is wrong. Verification methods also cannot make sure that the data entered is correct, they can make sure that is the same as what was written down but can give no certainty or accuracy.