Should We Launch Group Calling?

You work on a consumer calling product that currently supports only one-to-one calls. You have access to the following tables: `users` - `user_id` BIGINT - `country_code` STRING `calls` - `call_id` BIGINT - `caller_id` BIGINT - `recipient_id` BIGINT - `started_at` TIMESTAMP - `ended_at` TIMESTAMP - `status` STRING Assume `calls.caller_id` and `calls.recipient_id` both reference `users.user_id`, and all date-based analyses use the `Europe/London` timezone. Using only these existing one-to-one call logs, answer the following product analytics questions: 1. How would you determine whether the product should build a **group calling** feature? 2. If group calling is launched, how would you decide whether the launch was **successful**? In your answer, discuss: - how to infer unmet demand for group calls from one-to-one behavior - what proxy metrics you would build from call sequences and user networks - alternative explanations and confounding factors - what success means in terms of adoption, engagement, quality, and retention - the difference between launch metrics and long-term value metrics - how you would design an experiment, including randomization challenges from social-network interference - guardrail metrics and failure cases - how you would interpret mixed or ambiguous results