Topic 4: Validation & Verification Flashcards
What is validation of data?
Name and describe how one validation method could be used in a website registration form.
Validation is a process that ensures that data being input to a system is sensible and reasonable. A software developer will write a short piece of code that prevents data being entered if it doesn’t fit certain rules.
For example, a website registration form would require a presence check for essential fields such as name and address. A format check could be used to make sure a date of birth is entered as DD/MM/YYYY. And a range check could be used to ensure that the year of the date of birth makes sense for an adult between 16 and 99 years.
Give an example of data validation in a website registration form that requires ‘presence’.
A website registration form usually has a data validation check that prevents someone leaving a required field empty, such as first name or address.
What is verification of data? Give an example from a website registration form.
A verification check involves comparing two sources of the same data to ensure they are identical. An example from a website registration form is the need to enter a password twice (double entry).
Give an example of manual verification of data.
An employee proof reading data on a computer to ensure it is the same as the original paper source is an example of manual verification.
Why are validation and verification checks necessary?
Validation and verification checks are necessary in order to reduce the number of errors that get into a data system. The aim is to reduce the problem of ‘rubbish in, rubbish out’.
Do validation and verification checks ensure that data input into a system is perfect?
Validation and verification checks can only ensure that data is sensible and reasonable. Some incorrect data could get through because it meets the validation rules and it has been correctly input from the original source.
If a developer is very careful to code plenty of validation and verification checks, can they be sure that all customer addresses are correct?
No, because only the customer knows if the address is an old one or not. If the customer is asked to confirm their address, then this is a better verification check.
A website’s registration form has the following validation restrictions. What are they each called?
- post code must not be longer than 8 characters
- first name and last name must be completed
- age must be between 12-100
- the username must not already be in use
- Length check
- Presence check
- Range check
- File/table look-up
Data is sometimes entered incorrectly into a computer system. What is a transcription input error? Give two examples.
A transcription input error is a human error, for example due to a typing mistake, or misreading of handwriting
Data is sometimes corrupted when it is transmitted around a computer system. Describe how even parity is used to detect transmission errors.
Transmission errors can sometimes be detected using a parity check. For example, the binary code for the ASCII character C contains 3 1’s (1000011). An extra parity bit is therefore set to 1 before transmission so that the number of 1’s is even. This is called ‘even parity’. If the total number of 1’s at the receiving end is not even then an error must have occured.
A customer is trying to pay for goods on an ecommerce website. The payment form gives the following errors. What are these error checks called?
- Error! The long credit card number must not have letters or special characters
- Error! Your post code does not match the billing address you have entered
- Error! Your password entries do not match
- Error! You must enter a email address in the form xxx@xxx.xxx
- Type validation check
- Cross-field validation check
- Verification check
- Format check
