myZamana

myZamana grew from 100,000 to over 4 million users in under a year. The social network grew almost entirely through viral marketing. Traction cites it as its evidence for working on the viral coefficient.

The book's advice is to compute K as invites per user times conversion, and to split conversion into click-through and signup. Fix the weakest step first, since doubling either factor doubles K and shorter cycle times compound faster. A K near 0.5 in a test is promising, and the loop should keep being seeded from other channels. The quote: "Any viral coefficient above 1 will result in exponential growth". The book does not give myZamana's own coefficient.