Risk analysis (probability and impact) in Software Engineering - Mini Project: Build & Apply

Risk Analysis: Probability and Impact

📖 Scenario: You are part of a project team planning a new software product. To manage risks effectively, you need to list potential risks, assign their probability and impact scores, and then identify which risks need urgent attention.

🎯 Goal: Build a simple risk analysis table that shows each risk with its probability and impact scores, and then filter out the high-risk items that need immediate focus.

📋 What You'll Learn

Create a dictionary called risks with exactly these entries: 'Data loss': 0.3, 'Security breach': 0.6, 'Performance lag': 0.4, 'User error': 0.2, 'Hardware failure': 0.5

Create a dictionary called impact with exactly these entries: 'Data loss': 9, 'Security breach': 10, 'Performance lag': 6, 'User error': 3, 'Hardware failure': 7

Create a variable called threshold and set it to 4.0

Create a dictionary called high_risks that includes only risks where the product of probability and impact is greater than threshold

💡 Why This Matters

🌍 Real World

Risk analysis helps project teams focus on the most critical risks that could affect project success.

💼 Career

Understanding how to quantify and filter risks is essential for project managers, software engineers, and quality assurance professionals.

1

Set up the risk probabilities dictionary

Create a dictionary called risks with these exact entries: 'Data loss': 0.3, 'Security breach': 0.6, 'Performance lag': 0.4, 'User error': 0.2, 'Hardware failure': 0.5

Software Engineering

# Create the risks dictionary with given probabilities
# Your code here

Hint

Use curly braces {} to create the dictionary with the exact keys and values.

2

Set up the impact scores dictionary

Create a dictionary called impact with these exact entries: 'Data loss': 9, 'Security breach': 10, 'Performance lag': 6, 'User error': 3, 'Hardware failure': 7

Software Engineering

risks = {
    'Data loss': 0.3,
    'Security breach': 0.6,
    'Performance lag': 0.4,
    'User error': 0.2,
    'Hardware failure': 0.5
}
# Create the impact dictionary with given scores
# Your code here

Hint

Use a dictionary to map each risk to its impact score exactly as given.

3

Set the risk threshold value

Create a variable called threshold and set it to the float value 4.0

Software Engineering

risks = {
    'Data loss': 0.3,
    'Security breach': 0.6,
    'Performance lag': 0.4,
    'User error': 0.2,
    'Hardware failure': 0.5
}
impact = {
    'Data loss': 9,
    'Security breach': 10,
    'Performance lag': 6,
    'User error': 3,
    'Hardware failure': 7
}
# Set the threshold variable to 4.0
# Your code here

Hint

Just assign the number 4.0 to the variable named threshold.

4

Identify high-risk items

Create a dictionary called high_risks that includes only the risks where the product of probability from risks and impact from impact is greater than threshold. Use a dictionary comprehension with variables risk and prob iterating over risks.items().

Software Engineering

risks = {
    'Data loss': 0.3,
    'Security breach': 0.6,
    'Performance lag': 0.4,
    'User error': 0.2,
    'Hardware failure': 0.5
}
impact = {
    'Data loss': 9,
    'Security breach': 10,
    'Performance lag': 6,
    'User error': 3,
    'Hardware failure': 7
}
threshold = 4.0
# Create high_risks dictionary with risks having probability * impact > threshold
# Your code here

Hint

Use a dictionary comprehension to filter risks where probability times impact is greater than threshold.

Practice

1. What does risk analysis in software engineering primarily combine?

easy

A. The programming language and the software framework

B. The cost of the project and the team size

C. The number of developers and the project deadline

D. The likelihood of a problem and its potential impact

Solution

1. Step 1: Understand risk analysis components

   Risk analysis involves assessing how likely a problem is and how severe its consequences could be.

2. Step 2: Identify what is combined

   The two main factors combined are probability (likelihood) and impact (severity).

3. Final Answer:

   The likelihood of a problem and its potential impact -> Option D

4. Quick Check:

   Risk = Probability x Impact [OK]

Hint: Risk = chance of problem x how bad it is [OK]

Common Mistakes:

• Confusing risk with project cost
• Mixing team size with risk factors
• Thinking risk depends on programming language

2. Which formula correctly calculates the risk score in risk analysis?

easy

A. Risk score = Probability - Impact

B. Risk score = Probability + Impact

C. Risk score = Probability x Impact

D. Risk score = Impact ÷ Probability

Solution

1. Step 1: Recall risk score calculation

   The risk score is calculated by multiplying the probability of an event by its impact.

2. Step 2: Evaluate each formula

   Addition, subtraction, or division do not correctly represent risk score calculation.

3. Final Answer:

   Risk score = Probability x Impact -> Option C

4. Quick Check:

   Risk score uses multiplication [OK]

Hint: Multiply chance and impact for risk score [OK]

Common Mistakes:

• Adding probability and impact instead of multiplying
• Dividing impact by probability
• Subtracting values instead of combining

3. Given a risk with probability 0.3 and impact 8, what is the risk score?

medium

A. 8.3

B. 2.4

C. 0.375

D. 24

Solution

1. Step 1: Identify given values

   Probability = 0.3, Impact = 8.

2. Step 2: Calculate risk score by multiplying

   Risk score = 0.3 x 8 = 2.4.

3. Final Answer:

   2.4 -> Option B

4. Quick Check:

   0.3 x 8 = 2.4 [OK]

Hint: Multiply probability and impact numbers [OK]

Common Mistakes:

• Adding instead of multiplying
• Multiplying in reverse order but miscalculating
• Confusing decimal multiplication

4. A project manager calculates risk score as Probability + Impact instead of Probability x Impact. What is the main error?

medium

A. Using addition instead of multiplication for risk score

B. Ignoring the impact value

C. Using probability as a percentage

D. Calculating risk score twice

Solution

1. Step 1: Identify the calculation mistake

   The manager added probability and impact instead of multiplying them.

2. Step 2: Understand correct risk score formula

   Risk score must be calculated by multiplying probability and impact to reflect combined effect.

3. Final Answer:

   Using addition instead of multiplication for risk score -> Option A

4. Quick Check:

   Risk score = Probability x Impact, not addition [OK]

Hint: Risk score needs multiplication, not addition [OK]

Common Mistakes:

• Adding values instead of multiplying
• Forgetting to include impact
• Misinterpreting probability scale

5. A software project has three risks with these values: Risk A (0.2, 10), Risk B (0.5, 3), Risk C (0.1, 15). Which risk should be prioritized based on risk score?

hard

A. Risk A

B. Risk B

C. Risk C

D. All have equal priority

Solution

1. Step 1: Calculate risk scores for each risk

   Risk A: 0.2 x 10 = 2.0
   Risk B: 0.5 x 3 = 1.5
   Risk C: 0.1 x 15 = 1.5

2. Step 2: Compare risk scores to prioritize

   Risk A has the highest score of 2.0.

3. Final Answer:

   Risk A -> Option A

4. Quick Check:

   Risk A score = 2.0 > others [OK]

Hint: Pick risk with highest score [OK]

Common Mistakes:

• Choosing risk with highest probability only
• Choosing risk with highest impact only
• Assuming all risks have equal priority