OtherAt YC our motto is make something people want. But how do you actually know if you've accomplished that in the early days? One of the best ways to measure successful growth is a concept called cohort retention, which tracks the fraction of new users that come back time and time again to use your product. David Lieb explains how to define cohorts, track active users and determine the appropriate time frame for measuring successful retention rates.August 29, 2024 One of the biggest mistakes founders make is relying on aggregate user metrics instead of understanding how any individuals use their product. In this episode of Startup School, YC General Partner David Lieb walks through one of his favorite tools for better understanding your users, the dot plot. It's a simple two-dimensional grid that maps individual user activity over time and it can help separate signal from the noise in the early days of a startup. He'll cover why it gives founders a better sense of product health compared to aggregate metrics, what patterns to look for and real-world examples of how dot plots helped teams at Google Photos and PayPal.July 09, 2026