Product Design Questions
This section covers frameworks and worked examples for product design interview questions. For foundational concepts, see the Product Sense page.
CIRCLES Framework
| Step | Action | Key Question |
|---|---|---|
| Comprehend | Understand the situation | What problem are we solving? Who is asking? |
| Identify | Define the customer | Who are the users? What are their goals? |
| Report | State customer needs | What are their pain points? |
| Cut | Prioritize | Which needs matter most? |
| List | Generate solutions | What are possible solutions? |
| Evaluate | Analyze trade-offs | Which solution best addresses the need? |
| Summarize | Make recommendation | What is the recommendation and why? |
Worked Example: Improve Facebook Events
Prompt: "You're a PM at Facebook. How would you improve Facebook Events?"
Step 1: Comprehend
Clarifying questions:
- Mobile, web, or both?
- Focus on event creation, discovery, or attendance?
- Specific business goals (engagement, revenue, retention)?
- Target regions or demographics?
Assumptions: Mobile-first, focus on event discovery, users aged 25-40, goal is increasing engagement.
Step 2: Identify the Customer
| Persona | Description | Goals | Frequency |
|---|---|---|---|
| Social Butterfly | 28, urban professional | Find weekend activities with friends | Weekly |
| Event Organizer | 35, community leader | Promote events, maximize attendance | Monthly |
| Casual Browser | 32, parent | Discover family-friendly activities | Bi-weekly |
Primary focus: Social Butterfly (highest engagement potential, largest segment)
Step 3: Report Customer Needs
| Pain Point | Description | Severity |
|---|---|---|
| Discovery overwhelm | Too many events, hard to find relevant ones | High |
| Coordination friction | Difficult to see friend interest | High |
| Timing conflicts | No calendar integration | Medium |
| Quality uncertainty | Cannot assess event quality | Medium |
| Last-minute planning | Miss events of interest | Low |
Step 4: Cut Through Prioritization
Impact vs. effort analysis:
| Pain Point | Impact | Effort | Priority |
|---|---|---|---|
| Discovery overwhelm | High | Medium | 1 |
| Calendar integration | High | High | 2 |
| Friend coordination | Medium | Low | 3 |
| Quality uncertainty | Medium | Medium | 4 |
| Last-minute reminders | Low | Low | 5 |
Selected focus: Discovery overwhelm
Step 5: List Solutions
| Solution | Description | Pros | Cons |
|---|---|---|---|
| Personalized feed | ML-based event recommendations | Highly relevant | Cold start problem |
| Friend activity highlights | Show "5 friends interested" | Social proof | Privacy concerns |
| Interest-based categories | User-selected category follows | User control | Requires user action |
| Location-smart suggestions | Commute pattern analysis | Context relevance | Privacy concerns |
| Weekend planner | Curated top 5 weekly | Low cognitive load | Limited personalization |
Step 6: Evaluate Trade-offs
| Criteria | Personalized Feed | Friend Activity | Interest Categories | Location-Smart | Weekend Planner |
|---|---|---|---|---|---|
| User Impact | 5 | 4 | 3 | 4 | 3 |
| Technical Feasibility | 3 | 5 | 5 | 2 | 4 |
| Business Alignment | 5 | 4 | 3 | 3 | 3 |
| Privacy Risk | 3 | 2 | 5 | 1 | 5 |
| Total | 16 | 15 | 16 | 10 | 15 |
Selected solution: Personalized Feed
Rationale:
- Scales with user base growth
- Compounds engagement (more usage = better recommendations)
- Leverages Facebook's existing ML infrastructure
Step 7: Summarize
Recommendation: Build a personalized event feed for mobile users aged 25-40.
Key insight: Discovery overwhelm is the primary pain point. Users need relevant events without scrolling through hundreds of options.
Solution: ML-powered recommendations based on past attendance, friend activity, and stated interests.
Success metrics:
- Events discovered per session
- RSVP rate
- Actual attendance rate
Trade-off mitigation: Address cold start problem by requesting 3-5 interest categories during onboarding.
Question Type Reference
"Improve" Questions
| Question | Key Tensions |
|---|---|
| Improve Google Maps | Navigation vs. discovery vs. local business |
| Improve Instagram | Creators vs. consumers, engagement vs. well-being |
| Improve Amazon checkout | Conversion vs. trust vs. speed |
| Improve Spotify | Discovery vs. familiar, free vs. premium |
"Design for" Questions
| Question | Key Considerations |
|---|---|
| Design for elderly users | Accessibility, simplicity, trust |
| Design for emerging markets | Offline capability, low bandwidth, affordability |
| Design for kids | Safety, parental controls, age-appropriate content |
"Build a product" Questions
| Question | Key Challenges |
|---|---|
| Build a fitness app | Motivation, habit formation, hardware integration |
| Build a travel planner | Complexity, collaboration, real-time data |
| Build a neighborhood app | Trust, local relevance, chicken-and-egg |
Supporting Frameworks
GAP Analysis (for "Improve" questions)
| Component | Purpose |
|---|---|
| Goals | What are users trying to achieve? |
| Activities | What do they do today? |
| Pain points | Where do they struggle? |
RICE Prioritization
| Factor | Definition |
|---|---|
| Reach | Users affected |
| Impact | Experience improvement magnitude |
| Confidence | Estimate certainty |
| Effort | Development cost |
Score = (Reach x Impact x Confidence) / Effort
MVP Scoping
| Category | Inclusion Criteria |
|---|---|
| Must Have | Core functionality for hypothesis testing |
| Nice to Have | Polish, edge case handling |
| Future | Advanced features, optimizations |
Common Errors
| Error | Problem | Correction |
|---|---|---|
| Jumping to solutions | Shows shallow thinking | Spend 40% of time on problem definition |
| Listing 10+ features | Cannot prioritize | Focus on top 3, explain cuts |
| Ignoring trade-offs | Appears naive | State: "The downside is X, but we mitigate with Y" |
| Generic personas | Not actionable | Be specific: age, job, motivations, behaviors |
| No success metrics | Cannot evaluate | Define 2-3 metrics upfront |
Response Best Practices
| Practice | Example |
|---|---|
| Take time to structure | "Can I have a moment to structure my thoughts?" |
| State assumptions | "I'm assuming mobile-first targeting millennials" |
| Be opinionated | Make a choice and defend it |
| Use numbers | "If 10% of users have this problem and we solve 50% of cases, that's 5M affected users" |
| Draw flows | Sketch user flows or wireframes if whiteboard available |
| Connect to business | "This drives engagement, which leads to ad revenue through increased time in app" |
Practice Questions
- Improve: How would you improve WhatsApp for small businesses?
- Design for: Design a product for remote workers to stay connected with their team.
- Build: Build a product that helps people learn a new language.
- Prioritize: You have 5 features for Airbnb. How do you prioritize?