My latest book “Welcome to the Fifth Estate: How to Create and Sustain a Winning Social Media Strategy,” discusses influencer theory in detail, including a section on the history of influencer theory on the social Web. Since drafting that material, leaderboard debate about quantifying influence has dramatically shaped the conversation on influencer theory. This post looks at the state of influencer theory on the social Web specifically for SmartBrief on Social Media readers based on the book and recent developments.

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Successful online word-of-mouth or grass-roots marketing involves an attention phase in which community influencers embrace and spread the message. The dynamics of influence is a highly disputed topic. No one knows what’s going to go “viral.” But talking to the few and the passionate — your influencers, often leaders in the community — is always an ingredient, often at an early stage but certainly at some point during the upward trending curve.

For organizational social media, this means building credible relationships with contacts who have networks of the right people, not necessarily the most people. Leaderboard systems such as Klout and Empire Avenue can quantify individual social media capabilities and strength. Using these gamified leaderboard systems, companies and nonprofits can build lists of high-scoring voices and target them as influencers.

Many would argue that understanding your community’s dynamics and building relationships from within a community as a member of the Fifth Estate is a more reliable strategy than using a leaderboard list. Getting an idea embraced by those who can best spread the word often requires subject-matter expertise and accessibility, stronger grass-roots within a community.

The discussion about influence’s actual being has been ongoing since the social Web first began. As the infographic depicts (special thanks to JESS3 for providing the image), there are several theories influencing the professional conversation. This list of chronological descriptions also includes who generated the theory and some popular examples.

The Tipping Point (2000) by Malcolm Gladwell: Movements are caused by three types of influencers: connectors, mavens (subject-matter experts) and salesmen. Examples: Old Spice Guy, Dell Listens.

Six Degrees/Weak Ties (2003) by Duncan Watts: Data analysis shows influencers rarely start contagious movements; instead, average citizens provide the spark. Examples: Egyptian revolution, Tumblr – Digg events.

One Percenters (2006) by Jackie Huba and Ben McConnell: It is the content creators amongst Internet communities that drive online conversations. Examples: Lady Gaga, Ford Fiesta.

The Magic Middle (2006) by David Sifry: The middle tier of content creators and voices break stories, and discussing that trickles up into widespread contagious events. Examples: 2008 Obama election, Motrin Moms.

The Groundswell (2008) by Charlene Li and Josh Bernoff: Movements start within communities, and leaders rise up out of the community and can have many roles including content creator, critic and collector. Examples: Haiti earthquake texting, Pepsi Refresh Project.

Trust Agents (2009) by Chris Brogan and Julien Smith: Influencers are people who build online trust and relationships with communities that look to them for advice and direction. Examples: Gary Vaynerchuk’s Wine Library TV, Republican Party’s #FirePelosi campaign.

Free Agents (2010) by Beth Kanter and Allison Fine: These trusted influencers are independent of traditional command and control organizations and crash into walls of storied culture. Examples: @BPGlobalPR, Robert Scoble at Microsoft’s Channel 8.

Leaderboards (2010-11): Influence can be quantified by online actions taken by a person’s community, including retweets, mentions, comments and more. Examples: Klout, Empire Avenue.

These theories primarily fall into two camps. The Gladwell camp argues for an uber-influencer approach that has a select few types of people who can move networks and organizations toward action. One can argue that the One Percenter, Trust Agent, Free Agent and Leaderboard theories all expand or play off Gladwell’s original Tipping Point theory of three types of critical influencers, though the Free Agent theory has a unique element of independence to it.

The second camp plays off the Six Degrees theory originally offered by Watts, which holds that viral events are the result of individuals within a community, those who rise up at the right moment or on the right topic. Both Sifry’s Magic Middle and Li and Bernoff’s Groundswell theories have similar views of influence. While a much more egalitarian view of influence, it is important to note that all of these theories are based on empirical data of actual social networks.

To be sure, there are other influence theories. For example, some think influencers can be limited to a much smaller group known as Dunbar’s number: about 150 people; the concept was first proposed by British anthropologist Robin Dunbar. Dunbar’s theory acknowledges a cognitive limit to the number of people with whom one can maintain stable social relationships. But in reality, today’s business conversation about influence is dominated by an almost-decade-long debate between the Gladwell and Watts schools of theory about influence.

Back to today’s discussion on leaderboard quantification of influence: When considering the state of influencer theory, it is important to remember that leaderboards provide only a list and fail to accurately depict influence within a community based on all of the other theories — unless highly qualified by subject matter and the communities surveyed. When used within highly qualified topic areas and social networks, leaderboards help you quantify who are the uber-influencers in a Gladwellian sense. If you subscriber to a more democratized, networked influence model, then leaderboads are going to be of marginal value, instead requiring a deeper intimacy with communities of interest.

The dynamics of social-network technology continue to evolve. Someone’s clout can be taken away or affected by new networks — such Google+ — capabilities and influences. As communicators, we are only beginning to understand how pervasive mobile Web access has become, much less how this burgeoning trend affects our community influence patterns. Empirical scientific studies have only begun. While we try to force finite concepts onto this zeitgeist, we are at the same time evolving the way it works, changing our own information patterns as we seek to understand, evolve and expand this evergreen world.

The lesson? Remain teachable. The ability to adapt keeps us relevant.