“Garbage in, garbage out” – if wrong data goes into a computer, wrong information comes out. Validation and verification are two ways of reducing errors when data is entered.
This builds on Data and Information: information is only useful if the data behind it is correct.
Build on what you learned in Forms 1–3
These Lower School ICT posts cover the basics of this topic:
- Data and Information – why correct data matters for useful information
In this post:
- The difference between validation and verification
- Validation checks: range, reasonableness, data type, consistency, presence, format and length
- Verification methods: double entry and proofreading
- Choosing the right check for a scenario
Validation vs verification
| Validation | Verification |
|---|---|
| Done automatically by the computer | Done by people (or by comparing two entries) |
| Checks that data is reasonable/sensible and follows rules | Checks that data has been copied/entered accurately from the source |
| Cannot tell if data is actually correct – an age of 15 is valid even if the person is really 16 | Catches typing (typographical) and transposition errors, e.g. 1985 typed as 1958 |
Key idea: data can be valid but still wrong. Validation checks if it is allowed; verification checks if it matches the original.
Video: IGCSE ICT- Verification vs Validation – Theory Revision: Database #3 – – https://www.youtube.com/watch?v=OeHe61pT9CI
Validation checks
| Check | What it does | Example |
|---|---|---|
| Range check | Data must be between a lower and upper limit | A test mark must be 0–100 |
| Reasonableness check | Data must be sensible/realistic | A Form 4 student’s age should be about 14–18 |
| Data type check | Data must be the right type | Age must be a number, not “fifteen” |
| Consistency check | Related fields must agree | Date of graduation must be after date of birth; a male student cannot be in a girls’ school register |
| Presence check | Data must not be left blank | Student ID must be filled in |
| Format check | Data must follow a pattern | Date as DD/MM/YYYY; T&T phone number as 868-XXX-XXXX |
| Length check | Data must have a set number of characters | A student ID must be exactly 6 characters; a password at least 8 |
Verification methods
- Double entry: the data is entered twice (e.g. “confirm your password” or two typists) and the computer compares the two. If they don’t match, there is an error.
- Proofreading: a person reads the entered data and compares it with the source document to spot typographical and transposition errors.
Video: Data Verification Vs Validation – https://www.youtube.com/watch?v=iS9tqYuVQ08
For more videos, see Videos: Data Validation And Verification.
Try it: Which check?
Choose the check that would catch each error.
| A mark of 150 is entered for a test out of 100 | |
| The student ID field is left empty | |
| A date is entered as 2026/31/12 instead of DD/MM/YYYY | |
| “seventeen” is typed into the Age field | |
| A 7-character ID is entered where IDs have 6 characters | |
| A Form 1 student’s age is entered as 61 | |
| A clerk types 1958 instead of 1985 from a form; a second clerk types it correctly | |
| The date of leaving school is before the date of entry |
Paper 1 practice (multiple choice)
Choose the best answer for each question. Try them all before you check.
1. Which statement about validation is TRUE?
(A) It guarantees data is correct
(B) It is carried out by the computer to check data is sensible
(C) It involves typing data twice
(D) It is the same as proofreading
2. Entering a new password twice is an example of
(A) a range check
(B) double entry verification
(C) a format check
(D) a presence check
3. A check that ensures a field is not left blank is a
(A) presence check
(B) length check
(C) type check
(D) range check
4. Typing 6587 instead of 6578 is called a
(A) transposition error
(B) range error
(C) format error
(D) presence error
5. Which check would ensure a phone number follows the pattern 868-XXX-XXXX?
(A) Range
(B) Format
(C) Consistency
(D) Presence
Show answers
1. B
2. B
3. A
4. A
5. B
Paper 2 practice (structured question)
A school is creating an online form for students to register for CSEC exams. The form asks for Student ID (6 characters), Date of birth and Number of subjects (1–10).
(a) Distinguish between validation and verification. (2 marks)
(b) Suggest a suitable validation check for EACH field and explain what it checks. (3 marks)
(c) Explain why a validated date of birth could still be incorrect. (1 mark)
(d) Describe ONE method of verification the school could use. (2 marks)
Total: 8 marks
Show answers
(a) Validation is an automatic check by the computer that data is reasonable/obeys rules (1); verification checks that data has been entered accurately/matches the source (1).
(b)
• Student ID – length check (exactly 6 characters) or presence check (1)
• Date of birth – format check (DD/MM/YYYY) or range/reasonableness check (1)
• Number of subjects – range check, 1 to 10 (1)
(c) It may be a sensible date that follows the rules but is not the student’s actual date of birth (1).
(d) Double entry – data typed twice and the computer compares them (1) and flags mismatches (1); OR proofreading – a person compares the entered data with the source document (1) to find typing errors (1).
Next: File Organisation and Access Methods: Serial, Sequential, Direct and Random
Syllabus link: This post is relevant to the CSEC® Information Technology Syllabus (CXC 30/G/SYLL 17), Section 1: Computer Fundamentals and Information Processing, Specific Objective 13 (“differentiate between validation and verification of data”); Specific Objective 14 (“identify appropriate validation and verification checks given a particular scenario”).
Attributions to media used in this post:
No third-party images are used in this post. Embedded videos are credited on YouTube to their channels.
Updates
2026/10/16
– Shuffled the answer options in the “Try it: Which check?” activity so they no longer appear in the same order as the questions.
– Lists and algorithms laid out line by line.
© 2026 Vedesh Kungebeharry. All rights reserved.