In a recent study, Duncan Watts, Dan Goldstein, and I examined the adoption patterns of several different types of products diffusing over various online platforms — including Twitter, Facebook, and the Yahoo! IM network — comprising millions of individual adopters. The figure below shows the structure and frequency of the five most commonly seen diffusion trees in each case. In all six domains the dominant diffusion event, accounting for between 70% to 95% of cascades, is the trivial one: an individual adopts the product in question and doesn’t convert any of their contacts. The next most common event, again in all six domains, is an independent adopter who attracts a single additional adopter. In fact, across domains only 1%-4% of diffusion trees extend beyond one degree.
via Messy Matters – This Post Won’t Go Viral. Perhaps the more interesting aspect is that most adoptions occur without a peer-to-peer influence or within one step of the original peer.