{"blocks": [{"key": "77547e31", "text": "Scenario", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "4bc5a4c2", "text": "Short-video app (TikTok-like) – A/B testing a new recommendation algorithm.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "c7bf3f40", "text": "Question", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "576a9dc1", "text": "List the top three metrics you’d use to measure user engagement in a short-video feed.", "type": "unordered-list-item", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "2a825640", "text": "Design an A/B test for the new recommender: specify sample-size calculation, experiment duration, and stopping criteria.", "type": "unordered-list-item", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "fc93bb8e", "text": "Hints", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "17e2e520", "text": "Consider watch time per DAU, session starts, likes per view; use power analysis for size, minimum-detectable effect for duration.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}], "entityMap": {}}