Quality metrics and measurement in Software Engineering - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the sentence to define a common quality metric.

Software Engineering

The metric that measures the number of defects per thousand lines of code is called [1].

Drag options to blanks, or click blank then click option'

ADefect Density

BCode Coverage

CMean Time To Repair

DCyclomatic Complexity

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing it with code coverage which measures test completeness.

Defect Density measures how many defects are found per thousand lines of code, helping assess software quality.

2fill in blank

medium

Complete the sentence to identify a metric used to measure software reliability.

Software Engineering

The average time a system operates without failure is called [1].

Drag options to blanks, or click blank then click option'

ADefect Density

BCode Coverage

CMean Time Between Failures

DResponse Time

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing it up with Mean Time To Repair which measures repair duration.

Mean Time Between Failures (MTBF) measures the average operational time between failures, indicating reliability.

3fill in blank

hard

Fix the error in the definition of a metric that measures test thoroughness.

Software Engineering

The percentage of source code executed by tests is called [1].

Drag options to blanks, or click blank then click option'

ACode Coverage

BDefect Density

CMean Time Between Failures

DCyclomatic Complexity

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing it with defect density or reliability metrics.

Code Coverage measures how much of the source code is executed during testing, indicating test thoroughness.

4fill in blank

hard

Fill both blanks to complete the formula for Defect Density.

Software Engineering

Defect Density = [1] / [2]

Drag options to blanks, or click blank then click option'

ANumber of Defects

BLines of Code

CTest Cases Executed

DExecution Time

Attempts:

3 left

💡 Hint

Common Mistakes

Using test cases or execution time instead of code size.

Defect Density is calculated by dividing the Number of Defects by the Lines of Code to assess software quality.

5fill in blank

hard

Fill all three blanks to complete the description of Cyclomatic Complexity calculation.

Software Engineering

Cyclomatic Complexity = [1] - [2] + 2 * [3]

Drag options to blanks, or click blank then click option'

AEdges

BNodes

CConnected Components

DLines of Code

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing lines of code with graph elements.

Cyclomatic Complexity is calculated as the number of Edges minus the number of Nodes plus twice the number of Connected Components in the control flow graph.

Practice

1. What is the main purpose of quality metrics in software engineering?

easy

A. To manage project budgets

B. To write code faster

C. To measure and improve software quality

D. To design user interfaces

Solution

1. Step 1: Understand what quality metrics measure

   Quality metrics provide numbers that show how good or bad software quality is.

2. Step 2: Identify the main goal of using these metrics

   They help find problems and track improvements in software quality.

3. Final Answer:

   To measure and improve software quality -> Option C

4. Quick Check:

   Quality metrics = measure and improve quality [OK]

Hint: Quality metrics measure software quality, not speed or cost [OK]

Common Mistakes:

• Confusing quality metrics with project management tools
• Thinking metrics speed up coding directly
• Mixing quality metrics with design tasks

2. Which of the following is a correct example of a software quality metric?

easy

A. user interface color

B. number of developers

C. programming language used

D. defect density

Solution

1. Step 1: Identify what counts as a quality metric

   Quality metrics are measurable numbers related to software quality, like defects per size.

2. Step 2: Check each option

   Defect density counts defects per size, so it is a quality metric. Others are not numeric quality measures.

3. Final Answer:

   defect density -> Option D

4. Quick Check:

   Defect density = quality metric [OK]

Hint: Look for measurable numbers related to software quality [OK]

Common Mistakes:

• Choosing non-numeric attributes like color or language
• Confusing team size with quality metric
• Ignoring the need for measurement

3. Given a software module with 50 defects found in 10,000 lines of code, what is the defect density?

medium

A. 0.005 defects per line

B. 0.5 defects per line

C. 5 defects per line

D. 0.05 defects per line

Solution

1. Step 1: Understand defect density formula

   Defect density = Number of defects / Lines of code.

2. Step 2: Calculate defect density

   50 defects / 10,000 lines = 0.005 defects per line. This equals 0.005, which is 0.005 defects per line.

3. Final Answer:

   0.005 defects per line -> Option A

4. Quick Check:

   50 ÷ 10,000 = 0.005 [OK]

Hint: Divide defects by lines of code for defect density [OK]

Common Mistakes:

• Multiplying instead of dividing
• Mixing decimal places
• Confusing defect density with total defects

4. A team tracks test coverage but reports it as 150%. What is the likely error?

medium

A. Test coverage calculation is incorrect or data is wrong

B. Test coverage can exceed 100% if tests overlap

C. Test coverage is not a valid quality metric

D. Test coverage measures defects, not code tested

Solution

1. Step 1: Understand test coverage limits

   Test coverage measures percentage of code tested, max 100%.

2. Step 2: Analyze reported value

   150% is impossible, so calculation or data must be wrong.

3. Final Answer:

   Test coverage calculation is incorrect or data is wrong -> Option A

4. Quick Check:

   Test coverage ≤ 100% [OK]

Hint: Test coverage cannot be more than 100% [OK]

Common Mistakes:

• Believing coverage can exceed 100%
• Confusing coverage with defect count
• Ignoring data errors

5. A project has these metrics: defect density = 0.02, average repair time = 5 hours, test coverage = 80%. Which action best improves overall software quality?

hard

A. Ignore defect density and focus on coding speed

B. Increase test coverage to find more defects early

C. Reduce repair time without changing testing

D. Decrease test coverage to save time

Solution

1. Step 1: Understand the impact of each metric

   Higher test coverage helps find defects early, reducing defect density over time.

2. Step 2: Evaluate options for improving quality

   Increasing test coverage is the best way to improve quality by catching defects early.

3. Final Answer:

   Increase test coverage to find more defects early -> Option B

4. Quick Check:

   More test coverage = better defect detection [OK]

Hint: More test coverage usually improves quality by catching defects early [OK]

Common Mistakes:

• Focusing only on repair time
• Ignoring defect density
• Reducing test coverage to save time