Define Marketplace Success Metrics and Investigate Their Movement

A two-sided live-commerce marketplace asks you to define success metrics. A primary metric changes unexpectedly, and the team needs a diagnosis that distinguishes product impact from changes in buyers, sellers, inventory, and measurement.

Constraints & Assumptions

• Buyers can transact with multiple sellers and sellers can list multiple items.
• The metric may be a rate, so numerator and denominator must be investigated separately.
• Promotions and supply mix can change at the same time as product behavior.
• Late transaction and refund events can revise historical values.

Clarifying Questions to Ask

• Which marketplace decision will the metric support?
• Is success short-term conversion, healthy repeat behavior, liquidity, or contribution margin?
• At what grain and delay are orders, refunds, sessions, and listings considered complete?

Part 1 — Metric framework

Propose one primary marketplace metric and a compact set of buyer, seller, liquidity, quality, and economic guardrails.

What This Part Should Cover

• A defined unit, denominator, window, and inclusion rule
• Metrics connected through a causal funnel
• Counter-metrics that prevent one-sided optimization

Part 2 — Diagnosis

Lay out a query and analysis sequence for a sudden change in the primary metric.

What This Part Should Cover

• Logging and definition checks before causal stories
• Numerator-denominator decomposition
• Cohort, mix, supply, promotion, and latency analyses