Malcolm Gladwell who wrote The Tipping Point: How Little Things Can Make a Big Difference describes the “three rules of epidemics” (or the three “agents of change”) in the tipping points of epidemics.

• “The Law of the Few“, or, as Gladwell states, “The success of any kind of social epidemic is heavily dependent on the involvement of people with a particular and rare set of social skills.”According to Gladwell, economists call this the “80/20 Principle, which is the idea that in any situation roughly 80 percent of the ‘work’ will be done by 20 percent of the participants.”These people are described in the following ways:

• Connectors are the people who “link us up with the world … people with a special gift for bringing the world together.”They are “a handful of people with a truly extraordinary knack [... for] making friends and acquaintances”. He characterizes these individuals as having social networks of over one hundred people.

• Mavens are “information specialists”, or “people we rely upon to connect us with new information.” They accumulate knowledge, especially about the marketplace, and know how to share it with others. As Gladwell states, “Mavens are really information brokers, sharing and trading what they know”.

• Salesmen are “persuaders”, charismatic people with powerful negotiation skills. They tend to have an indefinable trait that goes beyond what they say, which makes others want to agree with them.

• The Stickiness Factor, the specific content of a message that renders its impact memorable. Popular children’s television programs such as Sesame Street and Blue’s Clues pioneered the properties of the stickiness factor, thus enhancing the effective retention of the educational content in tandem with its entertainment value.

• The Power of Context: Human behavior is sensitive to and strongly influenced by its environment. As Gladwell says, “Epidemics are sensitive to the conditions and circumstances of the times and places in which they occur”. For example, “zero tolerance” efforts to combat minor crimes such as fare-beating and vandalism on the New York subway led to a decline in more violent crimes city-wide.

From wikipedia