The viral coefficient is a measure of how many new users are brought in by each existing user.
It’s a quick and easy way to measure growth: if the coefficient is 1.0, the site grows linearly, and if it’s less than that, it will slow down. And if the coefficient is higher than 1.0, you will achieve exponential growth.
Source: Robert Zubek’s Blog
Author’s aside: Virality (not a real word) is one of the most overstated and misunderstood concepts in the business world. There are very few people who truly understand it and I do not purport to be one of them. Zubek’s post goes a long way towards demonstrating how virality is part art and part science. Remember, “something going viral” is an outcome rather than a marketing channel to be planned.
Further Related Reading:
- Lightspeed Ventures Blog: Viral Marketing = Free Customers
- Andrew Chen: Viral Coefficient
- Monifesto: Building and Measuring a Viral Loop
- Fast Company Worship/Blatant Promotion of Ning: Ning’s Infinite Ambition (The Viral Feedback Loop)