Metrics question

How would you measure the success of Facebook Marketplace?

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Tests metrics design for a marketplace feature: defining a north star tied to transaction completion, plus supporting and trust guardrail metrics.

State Marketplace's core value: helping buyers and sellers complete safe, local transactions, so success should track transactions, not just listings.
Propose a north star: completed transactions per active seller and buyer per month.
Add funnel metrics: listing creation rate, message response rate (buyer to seller), and time from message to completed transaction.
Add a trust guardrail: reported scam or fraud rate, and seller response rate, since trust failures kill a peer marketplace fastest.
Add a liquidity metric: median time to sell an item, since a healthy marketplace clears inventory reasonably fast.
Segment by category, since electronics, furniture, and vehicles will have very different transaction cycles and price points.

Chooses completed transactions, not listings created, as the north star, since listings alone can inflate without real marketplace health.
Adds message response rate as a funnel metric, since peer-to-peer marketplaces live or die on whether sellers actually respond.
Treats fraud and scam rate as an explicit guardrail, not an afterthought, given Marketplace's history of trust and safety issues.
Segments by category, recognizing that time-to-sell and price dynamics vary hugely between, say, furniture and electronics.

Using listing volume as the primary success metric instead of completed transactions.
Omitting fraud or trust metrics as a guardrail for a peer-to-peer marketplace.

How would you measure a transaction as completed if Facebook does not process payment?
How would you weigh growth in transactions against a rising fraud report rate?