1. Validation
Bury College

2. Input Devices What input devices are suitable for data entry? Keyboard
Microphone
Scanner
Mouse

3. Validation & Verification

4. Preventing errors
Validation & verification are used to prevent input errors!

5. What errors?????
The customer could make a mistake entering their date of phone number
The person entering the data could make a transcription error
The form may be lost
The form may be entered twice by mistake
The data could be lost due to network failure

6. What is Validation
Validation is a method of checking data to try to reduce the number of errors when data is input into a computer
It tests the data against the VALIDATION RULE and gives the user an ERROR Message if the data does not pass the test.

7. Types of Validation There are many different types of validation:
Presence Check
Range Check
Format Check
Length Check
List or Lookup Check
Crossfield Check
Check Digit

8. Presence Check
Is the simplest form of validation. It makes sure that some data has been entered in a field/cell.

9. Range Check
Checks that the data is within a certain range of letters or numbers.
For example, a phone price has to be a number between £50 and £500 - £70 would be allowed but £35 would not.

10. Format Check
Checks data follows the correct pattern. For instance, a product code might have to be three letters followed by three digits – PAF741 would be accepted, but PAF74 would not.
Can you think of another example?

11. Length Check
Makes sure that the correct number of characters has been entered.
Can you think of an example?
i.e. mobile phone number has 11 characters

12. Cross Field Check
Makes sure that two fields are always entered correctly each time are entered into a record.
For example, if a certain phone contract is only available on one network, it will be rejected if a different network is selected.

13. Check Digit
Is used to make sure long numbers, such as those generated by bar codes, are entered correctly.
A calculation is carried out suing the digits in the number and the check digit is the result of those calculations.
In an epos system, the scanner would usually show a red light and make a beeping noise if the check digit does not match.
(For those who want to know how this is done see the next three slides – you won’t be asked to work this out in the exam)

14. Verification (is in the exam)
Verification is the process of making sure that the data has been input correctly, but this involves entering the data again.
This is called ‘double entry’
Q. can you think of an example when you had to enter data twice?

16. Creating a new account with Amazon
Required to enter my address twice, to ensure that they match. This will show if I have made an error typing it in. If they don’t match, it will give an error message.
Also, required to enter my new password twice, to ensure that I haven’t made an input error. If they don’t match it will give an input error.
I won’t be able to proceed without the address matching and the password matching.