Data entered incorrectly can lead to wrong calculations, misleading reports and costly decisions. Proofing (validation) checks data as it is entered and alerts the user to possible errors before the data is saved.
2. Types of validation routines
Mandatory field check – ensures a required field is not left blank.
Format check – verifies that the data follows a specific pattern (e.g., email address, phone number).
Range check – confirms that a numeric value lies within an acceptable interval, e.g. $0 \leq \text{Score} \leq 100$.
Consistency check – compares related fields to ensure logical consistency (e.g., start date must be before end date).
Lookup (list) check – restricts entry to a predefined list of values.
Cross‑field validation – uses the value of one field to validate another (e.g., total = quantity × unit price).
3. Implementing validation in common ICT tools
3.1 Spreadsheets (e.g., Microsoft Excel, Google Sheets)
Use Data \cdot alidation features:
Select the cell or range.
Choose Data → Data \cdot alidation.
Set the criteria (Whole number, Decimal, List, Date, Text length, Custom formula).
Enter an error message that will appear when the rule is violated.
3.2 Databases (e.g., Microsoft Access, MySQL)
Define field properties and use validation rules in table design:
Set Required = Yes for mandatory fields.
Enter a Validation Rule such as Between 0 And 100 for a score field.
Provide a Validation Text to guide the user.
3.3 Word processors (e.g., Microsoft Word mail merge)
Use Content Controls with restrictions:
Insert a Plain Text Content Control.
Open Properties and set a Regular Expression pattern for format checking.
3.4 Web forms (HTML/JavaScript)
HTML5 provides built‑in validation attributes:
required – mandatory field.
type="email", type="date" – format checks.
min and max – range checks.
pattern="regex" – custom format validation.
4. Example validation rules
Field
Validation Type
Rule / Example
Error Message
Student ID
Format
Pattern: ^[A-Z]{2}\d{4}$ (e.g., AB1234)
Enter a valid ID (two letters followed by four digits).
Birthdate
Range
Must be a date before today.
Birthdate cannot be in the future.
Score
Range
$0 \leq \text{Score} \leq 100$
Score must be between 0 and 100.
Country
Lookup
List: {UK, USA, Canada, Australia}
Select a country from the list.
End Date
Consistency
End Date > Start Date
End date must be later than start date.
5. Testing validation routines
Before deploying a form or database, test each rule with:
Valid data – ensure it is accepted.
Invalid data – confirm the correct error message appears.
Boundary values – test the limits of range checks (e.g., 0 and 100 for scores).
Empty fields – verify mandatory checks work.
6. Common pitfalls and how to avoid them
Over‑restrictive rules – users may be blocked from entering legitimate data. Keep rules realistic.
Unclear error messages – provide specific guidance on how to correct the entry.
Missing validation on critical fields – always validate fields that affect calculations or decisions.
Inconsistent validation across platforms – ensure the same rules are applied in spreadsheets, databases and web forms.
7. Summary
Proofing through validation routines is a vital skill for ICT practitioners. By applying mandatory checks, format patterns, range limits, consistency rules, lookup lists and cross‑field validation, data entry errors can be dramatically reduced, leading to more reliable information and better decision‑making.
Suggested diagram: Flowchart showing the validation process – input → check → accept or display error → repeat until valid.