The Cold Start Problem: How to Start and Scale Network Effects

by Andrew Chen

To increase the Acquisition Effect, you have to be able to directly measure it. The good news is that viral growth can be rolled up into one number. Here’s how you calculate it: Let’s say you’ve built a new productivity tool for sharing notes, and after it launches, 1,000 users download the new app. A percentage of these users invite their colleagues and friends, and over the next month, 500 users download and sign up—what happens next? Well, those 500 users then invite their friends, and get 250 to sign up, who create another 125 sign-ups, and so on. Pay attention to the ratios between each set of users—1000 to 500 to 250. This ratio is often called the viral factor, and in this case can be calculated at 0.5, because each cohort of users generates 0.5 of the next cohort. In this example, things are looking good—starting with 1,000 users with a viral factor of 0.5 leads to a total of 2,000 users by the end of the amplification—meaning an amplification rate of 2x. A higher ratio is better, since it means each cohort is more efficiently bringing on the next batch of users. Once you have calculated this metric, you can use A/B testing and implement new product features to try to improve it. This might involve easier sharing to social media, or multiple SMS reminders after an invite is sent. Perhaps the landing page is optimized to ask for less information upfront to get prospective users to sign up in just a few clicks. If you increase the viral factor of your product to 0.6,...