This piece leaves me unconvinced that some products don't spread virally. It only shows that they didn't spread virally in the environments measured. I could li

This piece leaves me unconvinced that some products don't spread virally. It only shows that they didn't spread virally in the environments measured. I could list dozens of products and services that I know about and use only because of word of mouth (both on and off online). The problem for marketers is that identifying viral growth after the fact is easy, but trying to spark it is very difficult.