Q: What product metric would you track if you were launching a new feature like “Dark Mode”? A: I would first define the feature's goal — e.g., improving user engagement or reducing eye strain. Key metrics would include feature adoption rate, engagement time post-adoption, retention rates among users who enabled the feature, and any change in churn. I’d also use A/B testing to assess user satisfaction. Question 2 Q: How do you calculate 7-day retention using SQL? A: I use a cohort-based approach. I find the user’s signup date (Day 0), then check if the same user returns exactly 7 days later. I use CTEs to track both events and calculate the retention rate as Day7 users divided by Day0 users.