A lot of folks have asked for more details on the way we measured and optimized viral app growth in the Stanford class I co-taught recently. So here’s a bit more info on methodology for measuring virality and what it means for an app to “go viral.”
K-factor and R-zero
Terms like “K-factor” (contagion) and “R-zero” (reproduction rate) are often used to describe the growth rate of viral apps. These terms come from the fields of medicine and biology — they’re originally intended to describe the spread of of viral diseases, but they’re nice analogies for how web/SN apps grow. Some would even describe widgets and apps as “diseases” that have “corrupted” popular social networks like MySpace and Facebook! Of course, having worked at Slide and authored some FB apps of my own, that’s clearly not my belief… So, read on if you’re interested in viral apps!