Measure Most-Viewed URLs and Subscription Conversion Rates

Design a metrics system for a web application that reports its most-viewed URLs and subscription conversion rate. Explain event definitions, data collection, aggregation, and how users can interpret the results correctly. ### Part 1 — Most-Viewed URLs Define a view and URL identity, then describe how to compute top URLs over a requested time window. #### What This Part Should Cover URL normalization, raw versus unique views, duplicate events, time windows, and scalable count aggregation. ### Part 2 — Subscription Conversion Define the conversion numerator, eligible denominator, attribution window, and user or session identity. Explain how the system joins events and handles delayed conversions. #### What This Part Should Cover A coherent funnel or cohort definition, deduplication, time alignment, and avoiding misleading rates. ### Constraints Traffic scale, freshness, and exact business definitions are unspecified. Do not assume that every page view belongs in the conversion denominator or that a subscription event always belongs to the same day's traffic. ### Clarifying Questions - Are URL views page loads, route changes, sessions, or distinct visitors? - Which query parameters distinguish content, and which should be normalized away? - Is conversion measured per visitor, account, session, or eligible cohort? - How are bots, retries, cancellations, and late-arriving events treated? ```hint Fix the denominator before building the dashboard A precise numerator cannot rescue a conversion rate whose eligible population is undefined. ``` ### What a Strong Answer Covers - Explicit metric definitions and a durable event model. - Windowed top-URL aggregation and identity-aware conversion computation. - Freshness, late data, correctness checks, and transparent reporting. ### Follow-up Questions - How would a subscription several days after the first visit affect cohort reporting? - How would you detect that a client release stopped sending view events?