Why Data Checking Is Important

Computer programs often rely on user input, such as:

• Entering exam scores

• Typing passwords

• Filling out online forms

• Entering personal information

If incorrect data is entered, the program may produce incorrect results or system errors.

To prevent this, programs use validation and verification techniques.

What Is Validation?

Validation is the process of checking whether input data follows the required rules or format.

Validation ensures that data is reasonable and within acceptable limits.

However, validation does not guarantee that the data is correct.

Example:

If a student enters 150 as their exam score, validation can detect that the value is outside the allowed range.

Common Validation Techniques

Several methods are used to validate input data.

Validation TypeDescriptionExampleRange checkValue must fall within a specific rangeScore between 0–100Length checkInput must contain a certain number of charactersPassword lengthType checkEnsures correct data typeNumbers onlyPresence checkEnsures input is not emptyRequired fieldsFormat checkChecks pattern of dataEmail address format

These checks help prevent invalid input from entering the system.

What Is Verification?

Verification is the process of checking whether data has been entered accurately.

Verification ensures that data entered into the system matches the original data source.

Methods of Verification

Two common verification methods are used.

Double Entry Verification

The user enters the same data twice.

The system compares both entries.

Example:

Enter password → Confirm password

If both entries match, the data is accepted.

Visual Verification

The user checks data visually on the screen before confirming it.

Example:

Reviewing an online form before submitting it.

Validation vs Verification

FeatureValidationVerificationPurposeCheck if data follows rulesCheck if data is entered correctlyFocusData format and limitsAccuracy of data entryExampleRange checkDouble entry

Both methods help ensure data quality and reliability.

Why Data Checking Is Important

Validation and verification help:

• Reduce data entry errors

• Improve program accuracy

• Maintain reliable databases

• Prevent incorrect calculations

These techniques are widely used in databases, online forms and computer systems.

Exam Tip (2210 / 0478)

Students are commonly asked to:

• Define validation

• Define verification

• Give examples of validation checks

A common exam question is:

Explain the difference between validation and verification.

Practice Question

Explain one example of validation.

Answer

A range check ensures that input values fall within an acceptable range, such as exam marks between 0 and 100.

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