Validation & Verification

11.1.2.5 explain the difference between the terms verification and validation

Validation & Verification

Validation

Validation is an automatic computer check to ensure that the data entered is sensible and reasonable. It does not check the accuracy of data.

Examples

  

Types of validation

Type of validation

How it works

Example usage

Check digit

one or several digits in a code are used to check the other digits are correct

algorithm Luna check last digit in credit card,

bar code readers in supermarkets use check digits

Format check

checks the data is in the right format

a motobyke number in Kazakhstan is in the form NN NN LL where L is any letter and N is any number

Length check

checks the data isn't too short or too long

a password which needs to be eight letters long

Lookup table/ Lookup check

looks up acceptable values in a table

when entering a social network, it searches the database for an existing username,

there are only seven possible days of the week

Presence check

checks that data has been entered into a field

in most databases a key field cannot be left blank

Range check

checks that a value falls within the specified range

number of hours worked must be less than 50 and more than 0

Spell check

looks up words in a dictionary

when word processing

Character check

When a field has to contain a specific character or type of characters.

an e-mail address should contain an “@” sign

Type check

when a field has be of a certain data type

integer, float/real

 

Verification

Verification is performed to ensure that the data entered exactly maches the original source.

Verification methods:

1. Entering the data twice (Double entry)

Think about when you choose a new password, you have to type it in twice. This lets the computer check if you have typed it exactly the same both times and not made a mistake.  It verifies that the first version is correct by matching it against the second version. Whilst this can help to identify many mistakes, it is not ideal for large amounts of data. 

  • It would could take a person a lot of time to enter the data twice.
  • They could enter the same mistake twice and so it wouldn't get picked up. 
  • You would end up with two copies of the data.

Examples

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2 Checking the data on the screen against the original paper document (Proofreading data or Visual check)

This saves having to enter the data twice.  It can help pick up errors where data has been entered incorrectly or transposed. 

However, it isn’t always that easy to keep moving your eyes back and forth between a monitor and a paper copy. Also, if you are tired or your eyes feel 'blurry' then you might miss errors.

Examples

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3 Printing out a copy of the data and comparing the printout to the original paper document.

This is probably the easiest of the verification methods because you can have both copies side by side and scan both for mistakes. However, it can be time consuming if there is a large amount of data to check and if you do it too quickly, mistakes could be overlooked.
Examples

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Questions:


Exercises:

Ex.1 Test "Data validation and verification"

Ex. 2 Quiz "Validation check"


Exam questions:

Question. Explain what is meant by data validation. (Marks: 3) Answer:
  • data checked by computer/software (1), at time of entry (1), that it falls within limits/is reasonable/acceptable (1)

 

Question. Explain how a range check could be used to validate the reference number. (Marks: 2) Answer:
  • date of birth part can be checked (1), to ensure that it is a possible date (1)

 

Question. What is the name of the extra digit at the end of the reference number? (Marks: 2) Answer:
  • check digit (1)

 

Question. Explain how the extra digit at the end of the reference number can help to reduce errors. (Marks: 3) Answer:
  • arrived at by calculation (1), when entered again - calculation repeated (1), if not the same (1), error reported (1), any key error likely to be picked up (1) - any three points

 

Категория: Programming languages | Добавил: bzfar77 (02.04.2021)
Просмотров: 110 | Теги: Presence check, Range check, Format check, Lookup check, Length check, Type check, Spell check, validation, Check digit, verification, Character check | Рейтинг: 5.0/1
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