Validation and Verification

One topic which appears every year in the WJEC ICT exam is Validation and Verification. These revision cards will help you answer any questions about them

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  • Created by: Ollie
  • Created on: 11-05-10 19:39

What do they mean?

So what is Validation?

It is a check performed by a computer program during data entry. It is a process which ensures that data accepted for processing is sensible and reasonable

Validation is performed by the program being used and consists of a series of checks called validation checks

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Validation Checks

Validation checks are used to restrict the user as to the data they can enter. This in turn will result in smaller chance or data entry error

Each validation check has their own special use:

  • Data type checks - these check if the data being entered is the same type as the data type specified for the field
  • Presence checks - This checks to see if a field has been filled in, and if it hasn't and that field is requires, the data will not be processed
  • Length checks - this checks to see if the data entered fits the requires amount of characters
  • range checks - these check to see whether the data entered fits within a certain range. For example all college students are over 14 and therefore entering the number 14 or lower would not be allowed
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Limitations in error checking

Errors WILL ALWAYS occur. It is very easy for someone to spell a persons name wrong as there are many names that sounds similar however are spelt differently

In order to reduce errors it is best to:

  • reduce the amount of inputted data to a minimum. It is much more efficient to capture data using optical mark/character recognition or bar coding as it is automatic
  • Allow the user to type in their details
  • Allow a user to check their details and make any corrections
  • Use as many validation and verification methods as possible
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What is Verification?

This means checking the data entered into the ICT system matches the source of information perfectly

In other words when entering data into an ICT system from a form filled in by a customer, once entered the data on the ICT system matches the data on the form perfectly

This can be done by any of the following three methods:

  • Proof reading
  • Double entry of data
  • Sending back printouts
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Verification Methods

Proof reading: This invloves one user carefully reading what they have typed in and comparing it to the data from the data source for any errors. Any errors can then be corrected

Double entry of data: Two people entering the same data into the ICT system and only if the two sets are identical will they be accepted for processing. However this is very costly

Sending back printouts: Printing information out and sending it back in had copy to the supplier in the hope that they will spot any errors. An example is when a travel agent sends you a print out confirmation off the holiday and then the user can check for errors

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Exam tips

Dont get confused between valid data and correct data. They are NOT the same.

Valid data can still be wrong - valid data just means that data passes the validation rules

For example a data enterer may have entered a double figured age into a college database, however this might be the wrong age he has entered

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