Know and understand importance, characteristics and uses of appropriate validation including range check, character check, length check, type check, format check, presence check

15 Proofing

Topic map – Cambridge IGCSE ICT (Sections 1‑21)

Why validation is important (AO1, AO3)

• Stops incorrect or incomplete data being stored.
• Reduces later data‑cleaning costs.
• Ensures compliance with business rules, legal and safety requirements.
• Boosts user confidence and overall system reliability.

Proofing techniques required by the syllabus (AO1, AO2)

1. Automated validation checks

These are the six checks listed in Section 15.2 of the IGCSE ICT syllabus. They are performed by the software before data is accepted.

2. Spell‑check and grammar‑check

Most word‑processors, spreadsheets and presentation packages contain built‑in spell‑check and grammar‑check utilities. They form part of the proofing toolkit, but students must recognise their limits:

• Only words absent from the program’s dictionary are flagged – proper nouns, technical terms or new words may be marked as errors.
• Grammar suggestions follow generic rules and may not suit specialised writing styles.

3. Visual verification (manual proofing) (AO1, AO3)

Verification is the manual inspection of data after automated checks. It is distinct from validation and is essential where software cannot test every rule.

• Scanning printed output for typographical errors.
• Double‑entry of critical data (entering the same information twice and comparing the results).
• Peer‑review or “buddy‑check” of a spreadsheet, form or document before finalisation.

Automated validation checks – purpose, characteristics & examples (AO1)

Step‑by‑step validation process (AO2)

1. Identify the data element to be validated.
2. Decide which checks are applicable (e.g., a date field may need presence, type, range and format checks).
3. Define the validation rules (limits, patterns, required status).
4. Implement the checks in the application (client‑side, server‑side, or both).
5. Provide clear, specific feedback when a check fails.
6. Allow the user to correct the entry and re‑submit until all checks pass.

Practical examples (AO2)

Web‑based student registration form

• Student ID: presence, length (exactly 8 characters), character (numeric only).
• Date of birth: type (date), range (01‑01‑1900 to today), format (DD/MM/YYYY).
• Email: presence, format (standard email regex).
• Phone number: length (10 digits), character (numeric only).

Spreadsheet budgeting worksheet (non‑web example)

• Expense amount: type check (numeric), range check (≥ 0), format check (currency with two decimal places).
• Category: character check (list of allowed words such as “Travel”, “Supplies”, “Utilities”).
• Date: type check (date), format check (YYYY‑MM‑DD), range check (must be within the current financial year).
• Reference number: length check (exactly 6 characters), character check (alphanumeric).

Benefits of using multiple checks together (AO3)

Combining checks creates a layered defence against bad data. Example:

• Presence check guarantees the field is not empty.
• Type check ensures the entered value can be interpreted correctly.
• Range check confirms the value lies within acceptable limits.
• Format/character checks catch typographical or structural errors.

Common pitfalls to avoid (AO3)

• Relying only on client‑side validation – server‑side checks are essential for security.
• Vague error messages – users need specific guidance (e.g., “Enter a number between 1 and 100”).
• Hard‑coding limits that may change – use configurable parameters where possible.
• Neglecting localisation – date, time and number formats differ between regions.
• Assuming spell‑check/grammar‑check will catch all errors – always finish with visual verification.

Suggested diagram

Key take‑aways (AO1)

1. Proofing protects data integrity and reduces errors.
2. Each validation check targets a specific aspect of the data.
3. Effective proofing combines automated checks, spell/grammar tools, and manual visual verification.
4. Implement validation on both client and server sides and test with real users.

Connections to other syllabus sections (AO1, AO2)

Validation checks are used throughout the ICT curriculum:

• Section 18 (Databases) – field constraints (type, length, range) are defined when designing tables.
• Section 19 (Spreadsheets) – data‑validation rules prevent wrong entries in financial models.
• Section 20 (Web authoring) – HTML forms and JavaScript use the same six checks to ensure clean user input.

Assessment Objective mapping (AO1‑AO3)

• AO1 – Knowledge: recall the six validation checks, the role of spell‑check/grammar‑check, and the purpose of manual verification.
• AO2 – Application: apply the appropriate checks to a given scenario (e.g., registration form, budgeting spreadsheet).
• AO3 – Analysis/Evaluation: evaluate the reliability of a solution by discussing strengths and limitations of the chosen proofing techniques.