← VCE Software Development U4O1

Validation versus verification

Validation checks entered data is reasonable and complete. Verification checks it matches the source data, for example by proofreading.

Part of: VCE Software Development - U4O1 - development and evaluation — Module 137, IGCSE Computer Science 0478 — 2.2 Methods of Error Detection — Module 31, IGCSE Computer Science 0478 — 7a Program Development Life Cycle — Module 51, ACARA Digital Technologies Years 9–10 — Acquiring and Validating Data — Module 64, QCE Digital Solutions Unit 2 — Data-Driven Problems and Solution Requirements — Module 19, QCE Digital Solutions Unit 2 — Data and Programming Techniques — Module 105, QCE Digital Solutions Unit 2 — Prototype Data Solutions — Module 82, QCE Digital Solutions Unit 3 — Innovative Digital Solutions — Module 61, WA Computer Science ATAR Year 11 — Control Structures and Data Types — Module 87

Understanding Validation versus verification in VCE Software Development U4O1

What it does: An existence check tests that data was entered at all, without comparing it to a source, so it is validation. Data can pass validation and still be wrong. For example, a mark of 70 instead of 80 is still reasonable. The code compares what was typed with the source data to confirm it was copied accurately, so it is verification. The message should say the mark is valid. To verify, the entered mark would have to be compared with the original source.

Common mistakes: A validation function is a normal function, so the def line must end with a colon: def is_valid_age(age):. Double entry verification compares the two entries. = assigns a value and is invalid in an if condition. Use == to compare.

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Learning

Duo

Which check confirms that an entered age is a number between 0 and 120?

ValidationVerification

Matches

if mark >= 0 and mark <= 100: print("Verified: matches the source")

↓

A range check is validation, not verification. It checks the mark is reasonable but does not compare it to the source data.

Applying

Meanings

Term

validation vs verification

Meaning

Validation checks entered data is reasonable and complete. Verification checks it matches the source data, for example by proofreading.

Practice

age = 16

Testing

Gaps

if 0 <= age 120:

Check Answer

Spots

1def is_valid_age(age)

2 return 0 <= age <= 120

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Quick Questions

1. Which check confirms that an entered age is a number between 0 and 120?

A. Validation ✓

B. Verification

Validation checks that data is reasonable and complete. A range check on age is a validation check.

2. Which check confirms that the data typed in matches the original paper form?

A. Verification ✓

B. Validation

Verification compares entered data with the source data. Validation cannot tell if the entry matches the form.

3. A student enters 25 as their age, but their paper form says 15. Both values pass a range check. Which statement is true?

A. Verification passes but validation would catch the error

B. Validation passes but verification would catch the error ✓

25 is a reasonable age, so validation passes. Only comparing it with the source form (verification) finds the mistake.

4. Proofreading entered data against the source document is an example of:

A. Verification ✓

B. Validation

Proofreading is a manual way to verify data. A person compares what was entered with the source data.

5. A program rejects an empty email field with an existence check. This is:

A. Verification

B. Validation ✓

An existence check makes sure that required data has been entered. This is validation because it checks completeness, not accuracy against the source.

Match the Pairs

if age < 0 or age > 120: → Validation: a range check that tests whether the entered age is reasonable

if entered == source_copy: → Verification: checks that the entered data matches the original source data

Validation checks that data is reasonable and complete, for example that a required field is not empty → if name == "": print("Name is required")

Verification by double entry: the user types the data twice and the two entries must match → if email1 != email2: print("Entries do not match")

if mark >= 0 and mark <= 100: print("Verified: matches the source") → A range check is validation, not verification. It checks the mark is reasonable but does not compare it to the source data.

Proofreading confirms a value is within an allowed range. → Proofreading is verification: it compares the entered data with the source. It does not test whether a value is reasonable or in range.

Key Term

validation vs verification

Validation checks entered data is reasonable and complete. Verification checks it matches the source data, for example by proofreading.

Fill in the Blanks

1. if 0 <= age <= 120:

Hint: Type the comparison operator that keeps age at or below the upper limit of this validation range check.

2. email = input("Email: ") again = input("Re-enter email: ") if email == again:

Hint: Verification by double entry: type the operator that tests whether the two entries are equal.

3. if len(name) > 0:

Hint: Validation existence check: type the built-in function that returns how many characters a string has.

4. if age < 0 or age > 120: print("Invalid age")

Hint: Validation range check: type the logical operator that makes the test succeed when either limit is broken.

5. source = "Ava Nguyen" typed = input("Retype name: ") print(source == typed)

Hint: Verification compares entered data with the original. Type the variable that holds the source data.

Spot the Error

Question 1

A def is_valid_age(age)

B return 0 <= age <= 120

C print(is_valid_age(25))

Line A — A validation function is a normal function, so the def line must end with a colon: def is_valid_age(age):

Question 2

A pw1 = input('Password: ')

B pw2 = input('Re-enter: ')

C if pw1 = pw2:

D print('Verified')

Line C — Double entry verification compares the two entries. = assigns a value and is invalid in an if condition. Use == to compare.

Question 3

A mark = int(input('Mark: '))

B if mark >= 0 or mark <= 100:

C print('Valid')

D else:

E print('Invalid')

Line B — This range check must use and, because a mark has to be at least 0 and at most 100. With or, every number passes, so invalid data is never rejected.

Question 4

A name = input('Name: ')

B while name == '':

C name == input('Name: ')

D print('Hello', name)

Line C — This existence check must store the new input. == only compares, so name never changes and the loop never ends. It should be name = input('Name: ').

Question 5

A source = 'S1042'

B typed = inpt('ID: ')

C if typed == source:

D print('Matches source')

Line B — The function name is misspelled. It must be input(), otherwise Python raises a NameError and the typed data can't be verified against the source.

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