A viral coefficient is the number of new community members, on average, that each community member brings to the community. A viral coefficient of 1 means that each member will bring 1 additional member to the community. One of the secrets to quickly grow social media properties is to maintain a viral coefficient greater than 1. Here are some examples of member growth rates at different viral coefficients:
(1) Viral Coefficient of 0.5 – If a community has 100 members and a viral coefficient of 0.5, then those 100 members will bring 50 new members to the site. Those 50 members will bring 25 members, and so on, and the community will ultimately plateau at about 200 members (after 10 periods of time). A social network with a viral coefficient less than 1 will stop growing on its own.
(2) Viral Coefficient of 1 – If a community has 100 members and a viral coefficient of 1, then those 100 members will bring 100 new members to the site, and those members will bring another 100 members to the site. This will result in linear growth from 100 to 200 to 300 until the community has reached 1,000 members in the same 10 periods of time as the first example.
(3) Viral Coefficient of 2 – If a community has 100 members and a viral coefficient of 2, then those 100 members will bring 200 members, who will bring 400 members, who will bring 800 members, etc. By the 10th period of time, this social network will have 51,200 members. Having a viral coefficient is like compound interest for social networking.
Fast-growing social media sites, such as Twitter, sometimes forgo advertising during their growth stage in order to maximize their viral coefficient and accelerate their exponential growth. Here are a couple of core principles to improve and maintain strong viral coefficients:
(1) Create something useful that people want to share with others: The viral coefficient will improve if sharing the information will make the sharer look better or improve their relationships with friends. Also, if the product is simple, easy-to-understand, free and web-based the “barrier of entry” and “friction” will be reduced and the viral coefficient will generally increase.
(2) Create a reason for people to share the message with others: FamilyLink.com members want to invite more family members so that they can know about important happenings in the lives of these people. Fans of a charity may be motivated to solicit their friends to donate to a charity about which they are passionate.
(3) Make it easy for people to share the message with others. Viajamos.com.br allows members to easily invite friends from their email or easily post a cool piece of content to Twitter. FamilyLink.com makes it easy to invite family members on Facebook, and also suggests other members to whom members may be related.
Here’s an article explaining how to calculate viral coefficients.
Posted on March 1st, 2010 by Nathan Gwilliam
Filed under: Online Communities, Social Media, Social Networking, Viral Marketing, e-Business
Great article. I really enjoyed it.
Good article. Simple explanation. One thing to note, the viral coefficient of each website/marketing campaign changes over time. If it was constant, the site would grow in perpetuity which is not the case. One of the factors those affect viral coefficient is “newness” of content. That, in turn, affects the infection rate of a viral effort.