← VCE Data Analytics U4O1

Verifying data

Checking that data was entered or copied exactly as it appears in the source, such as by double entry or comparing it with the original. It checks accuracy, not reasonableness.

Part of: VCE Data Analytics - U4O1 - Development and Evaluation — Module 80, IGCSE Computer Science 0478 — 7a Program Development Life Cycle — Module 64

Understanding Verifying data in VCE Data Analytics U4O1

What it does: The entered value 54 does not match the source value 45, so verification fails even though 54 is a sensible number. The system tested whether the value was reasonable, not whether it matched the source. That is validation. Double entry is a verification method. Any difference between the two entries shows a possible typing error. Visual comparison means checking the entered data against the original by eye. A whole-number rule is validation. Verification only confirms that data matches its source. If the source itself is wrong, verification will not detect it. Double entry verifies data by entering it twice independently and comparing the results to find differences.

Common mistakes: A single = assigns a value, so it cannot compare the two entries. Double entry needs the comparison operator: if first == second:. This branch runs when the two entries are different, so the message must report a mismatch. It should be print("Mismatch").

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This module's key terms are also in a printable crossword (Modules 63–83) and word search (Modules 63–105).

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Learning

Duo

Which check confirms that data was typed in exactly as it appears on the paper source form?

ValidationVerification

Matches

Age range check passed, so the data has been verified

↓

A range check is validation, not verification. It does not confirm the data matches the source.

Applying

Meanings

Term

verification

Meaning

Checking that data was entered or copied exactly as it appears in the source, such as by double entry or comparing it with the original. It checks accuracy, not reasonableness.

Practice

first <- INPUT("Enter student ID")

Testing

Gaps

=IF(A2B2,"Match","Re-check")

Check Answer

Spots

2second = input("Again: ")

3if first = second:

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Quick Questions

1. Which check confirms that data was typed in exactly as it appears on the paper source form?

A. Validation

B. Verification ✓

Verification checks that the entered data matches the source. Validation only checks that data is reasonable or allowed.

2. A student enters 250 for a Year 12 student's age and the system rejects it as too high. Which check was this?

A. Validation (a range check) ✓

B. Verification

The system tested whether the value was reasonable, not whether it matched the source. That is validation.

3. Two different people type the same survey forms into separate files and the files are compared. What is this called?

A. Range checking

B. Double entry ✓

Double entry is a verification method. Any difference between the two entries shows a possible typing error.

4. The source says a mark is 78. You type 87. Validation passes it as a number from 0 to 100. Will verification catch the error?

A. Yes, because 87 does not match the source ✓

B. No, because 87 is a valid mark

Verification compares the entered value with the source. Validation cannot detect this error because 87 is a reasonable value.

5. Which is an example of visual comparison with the source?

A. Reading each entered row alongside the original form to check it matches ✓

B. Setting a rule that only allows whole numbers in a column

Visual comparison means checking the entered data against the original by eye. A whole-number rule is validation.

Match the Pairs

Double entry: two people type the same records, then the two copies are compared → A verification method where mismatches between the two typed copies show where a data entry error was made

Visual comparison: read the entered data against the source document → A verification method where a person checks each entered value matches the original source exactly

Verification checks that data matches the source exactly, not that it is sensible → Source: 45 Entered: 54 -> verification fails

Validation checks data is reasonable and allowed, but cannot tell if it matches the source → Age must be between 0 and 120 -> 54 passes validation

Age range check passed, so the data has been verified → A range check is validation, not verification. It does not confirm the data matches the source.

Source: Smith Entered: Smyth -> data is verified because it is text → Verification requires an exact match to the source. Smyth differs from Smith, so the data is not verified.

Key Term

verification

Checking that data was entered or copied exactly as it appears in the source, such as by double entry or comparing it with the original. It checks accuracy, not reasonableness.

Fill in the Blanks

1. =IF(A2=B2,"Match","Re-check")

Hint: Type the operator that tests whether the first and second entries are equal.

2. =EXACT(A2,B2)

Hint: Type the function name that checks two text values are exactly the same.

3. first = "S1043" second = "S1043" print(first == second)

Hint: Type the operator that compares the two double entries for equality.

4. if entry1 != entry2: print("Mismatch: check source")

Hint: Type the operator that detects when the two entries differ.

5. =SUMPRODUCT(--(A2:A9<>B2:B9))

Hint: Type the 'not equal to' operator used to count mismatches between two columns.

Spot the Error

Question 1

A first = input("Enter ID: ")

B second = input("Again: ")

C if first = second:

D print("Verified")

Line C — A single = assigns a value, so it cannot compare the two entries. Double entry needs the comparison operator: if first == second:

Question 2

A entry1 = input("Entry 1: ")

B entry2 = input("Entry 2: ")

C if entry1 != entry2:

D print("Entries match")

Line D — This branch runs when the two entries are different, so the message must report a mismatch. It should be print("Mismatch").

Question 3

A source = Ava Nguyen

B typed = input("Name: ")

C match = typed == source

D print(match)

Line A — The source text is a string, so it must be in quotes. Without them Python reads Ava and Nguyen as variable names. It should be source = "Ava Nguyen".

Question 4

A source = [12, 45, 78]

B typed = [12, 45, 78]

C if len(source) == len(typed):

D print("Verified")

Line C — Comparing only the length does not show that each value was copied exactly. Verification must compare the actual data: if source == typed:

Question 5

A source = "AB123"

B typed = input("ID: ").lower()

C match = typed == source

D print(match)

Line B — Changing the case alters what was typed, so it may no longer match the source exactly. Verification checks an exact copy, so it should be typed = input("ID: ").

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