Data Validation

Do Now! Recap on the previous lesson about data types

Knowledge Intention

In this lesson, you will learn about:

  • validation and verification
  • the purpose of validation and verification
  • validation and verification tools
  • how validation and verification tools can reduce errors. 

Data validation means checking the accuracy and quality of source data before using, importing or otherwise processing data. Different types of validation can be performed depending on destination constraints or objectives. Data validation is a form of data cleansing.

Validation Tools Include

Data Type Check

Format Check / Input Mask

Length Check

Limited Choice

  • drop down list
  • radio buttons
  • tick list
  • lookup
  • presence check
  • range check

Example of a range check. Someone born in 1872 would be 150 years old.

Practical Starter Task

Find an online form and try and put some silly data, for example, say you were born in 1563.

Also, watch out for data types

Example, buy a train ticket

Register for BBC (don’t press submit)

Sign up for BBC

Data Validation

  • checks that the data being entered into a digital system is sensible and reasonable 
  • does not check that the data is correct
  • checks the data against pre-set rules
  • is usually carried out by the digital system at the point at which the data is being entered
  • is usually set as part of the creation of a solution.

Validation Tools Task

Look at the table below for validation tools and their purpose. Look at the examples for each one.

Radio button

Drop down list, the user has to choose one of the options

Postcode field uses an input mask to check that the format is correct


Create or download a worksheet and write the purpose of each validation tool.

Data Verification

  • makes sure that the data entered exactly matches the original source
  • but, as with validation, verification does not check the data is correct.

Double Entry

  • The data is entered twice
  • The data is then checked by comparing the two sets of data to make sure they are the same.
  • The comparison can be done manually by a person or through a check by the digital system. 
  • Manual double entry can be done by the same person or different people. 
  • An example of digital system double entry verification is entering a new password twice. 

Manual Checking

  • This is basically proofreading.
  • The source data is compared with the data entered into the digital system. 
  • Manual verification checks can be time consuming and expensive in terms of workload.

Question Time

  1. What is the purpose of validation?
  1. Length check is one validation tool. Identify two other validation tools.
  1. How can the length check validation tool reduce errors?
  1. Which validation tool should be used with a telephone number?
  1. Describe one disadvantage of manual verification.

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