Data integrity: correctness
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. A student types the value 'Mia' into the Age field of a database. Which integrity feature does this break?
2. Which entry is in the right form for a field that stores Quantity as a whole number?
3. A spreadsheet total uses =SUM(B2:B8) but the data runs from B2 to B9. What is the result?
4. Which method best checks that a calculation is correct?
5. A shop records a pencil price as $1.50, but the real price is $1.80. The value is in the right field and form. Which feature is the issue?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1Phone number typed into the Email field | AThis is an accuracy error: the value does not match the real world. It is not a field or form error, so the fix is to enter 72. | |
| 2=SUM(B2:B9) used where AVERAGE was needed | BAge (integer): 16 | |
| 3Correct data is in the right form, so an age is stored as a number, not text | CThe value is in the wrong field, so it is incorrect. Move 95 to the Mark field. | |
| 4Checking a calculation by working out a few results by hand to confirm the right result | DCheck: 88 + 74 + 81 = 243, and the sheet shows 243 | |
| 5Mark: 95 stored in the Student Name field | EA correctness error: the value is in the wrong field | |
| 6A student scored 72 but 27 was typed. The data is called incorrect because it is not correct. | FA correctness error: processing gives the wrong result |
C
Definitions
correctness
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
SELECT _________ FROM students
WHERE studentId = 1;
2.
DECLARE yearLevel AS _______
3.
=_______(B2:D2)
// mean of Ava's three marks
4.
=C2_D2
// total stock value of the pencils
5.
height ← 172 // real height is 175 cm
// Correct form, but not ________
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
lastName ← 'Ava'
B
yearLevel ← 7
C
OUTPUT firstName, yearLevel
Question 2
A
price ← 4.50
B
qty ← '3'
C
total ← price * qty
D
OUTPUT total
Question 3
A
total ← 88 + 74 + 81
B
average ← total / 2
C
OUTPUT average
Question 4
A
mark1 ← 88
B
mark2 ← 74
C
mark3 ← 81
D
total ← mark1 + mark2 + mark2
E
OUTPUT total
Question 5
A
SELECT firstName, house
B
FROM students
C
WHERE house > 100;
Answer Key
Data integrity: correctness
Section A: Quick Questions
Q1
B — Correctness: the value is in the wrong field
Q2
B — 12
Q3
A — Processing is incorrect, as the total leaves out a row
Q4
A — Work out the expected result by hand and compare it with the output
Q5
A — Accuracy: it is not close to the real-world value
Section B: Match the Pairs
Q1
Phone number typed into the Email field → A correctness error: the value is in the wrong field
Q2
=SUM(B2:B9) used where AVERAGE was needed → A correctness error: processing gives the wrong result
Q3
Correct data is in the right form, so an age is stored as a number, not text → Age (integer): 16
Q4
Checking a calculation by working out a few results by hand to confirm the right result → Check: 88 + 74 + 81 = 243, and the sheet shows 243
Q5
Mark: 95 stored in the Student Name field → The value is in the wrong field, so it is incorrect. Move 95 to the Mark field.
Q6
A student scored 72 but 27 was typed. The data is called incorrect because it is not correct. → This is an accuracy error: the value does not match the real world. It is not a field or form error, so the fix is to enter 72.
Section C: Definitions
Q1
correctness — Each value is entered in the right field and right form, and processing gives the right result. It differs from accuracy, which is how close a value is to the real world.Section D: Fill in the Blanks
Q1
SELECT firstName FROM students
WHERE studentId = 1;Q2
DECLARE yearLevel AS INTEGERQ3
=AVERAGE(B2:D2)
// mean of Ava's three marksQ4
=C2*D2
// total stock value of the pencilsQ5
height ← 172 // real height is 175 cm
// Correct form, but not accurateSection E: Spot the Error
Q1
A — Ava is a first name, but it was entered in the lastName field, so firstName is never set and the output is wrong. It should be firstName ← 'Ava'.
Q2
B — Quantity was entered as text instead of a number, so price * qty cannot give a correct result. It should be qty ← 3.
Q3
B — There are three marks, so the total must be divided by 3. Dividing by 2 gives an incorrect average, and checking the calculation by hand would show this.
Q4
D — The calculation adds mark2 twice and leaves out mark3, so the processing gives the wrong total. It should be total ← mark1 + mark2 + mark3.
Q5
C — house holds text such as 'Red', so it is the wrong field to compare with the number 100. The condition should use the points field.