Choosing a north-star metric and guardrails for ads shown in Facebook Reels

You own the ads product inside Facebook Reels as its product manager. Define how you would judge whether it is succeeding. ```hint Count the sides Reels ads touch viewers, advertisers and, for some formats, the creators whose videos carry the ad. A metric set that only shows more ads being sold can hide a worse experience for one of those sides. ``` ### Clarifying Questions - Does "ads in Reels" mean full-screen ads served between Reels, overlay ads placed on creators' Reels, or both? - Is the product still ramping, where the goal is to grow ad volume, or mature, where the goal is to earn more from each minute watched? - Is the scope Facebook Reels only, or Reels ad inventory shared with Instagram? - If creators receive a share of the revenue from ads on their Reels, should their outcomes count toward success? ### What a Strong Answer Covers - The goal of Reels ads, tied to Facebook's mission and to viewing time shifting toward short video - Metrics for each side (viewers, advertisers, creators), organized so a change in revenue can be explained - One north-star metric, with the reason it beats the alternatives - Guardrails against heavier ad load, cannibalization of other placements and worse advertiser results - How the metrics would be read in practice: experiments, holdouts and long-term effects ### Follow-up Questions - An ad-load increase lifts your north star, but Reels time per user dips slightly. How do you decide whether to keep it? - How would you tell whether ad spend in Reels is new money or budget moved from Feed and Stories? - Which of your metrics would you change if overlay ads on creators' Reels became the main format?