Influence marketing and the raft of tools available to measure social media influence have provoked a rumbling debate around the blogosphere in recent weeks. Tools that allow marketers to see how much ‘influence’ users of Twitter, Linkedin and Facebook exert across the social media world have split opinion.

In terms of reaching key influencers and demonstrating ROI on a social media strategy, having a clear metrics that demonstrate how deeply and effectively an individual or brand can affect the behaviour of others could be very useful; more useful still if there’s then a clearly defined way to take your brand to these influencers, in a targeted way.

It’s not the analytical effectiveness of the tools that has provoked debate, but the definition of ‘influence’, and the value that this information truly represents to marketers.

Does having an impressive Klout Score, for example, mean that a brand’s tweets can really influence behaviour, or does it simply demonstrate that they’re making a lot of noise across a wide bandwidth of the Twitterverse?

Critics might point out that popular singer and renowned crazy hat-wearer Lady Gaga, for instance, despite having an impressive Klout score of 92, is not likely to be a useful key influencer in, say, the financial services sector.

Fair enough, but a lot of the criticism over-simplifies what tools like Klout and PeerIndex represent for the future of influence and wider social media marketing. What they provide is a cleverly calculated and imaginatively represented bunch of analytics around a particular definition of influence.

As with any analytics, their effective application depends on the creativity of the marketer and, to an extent, how well that marketer understands their industry.

Azeem Azhar, CEO of Peer Index and Garth Holsinger, VP of Sales and Business Development at Klout will be joined by industry experts on 29 March, Day One of Social Media World Forum Europe 2011, in London to discuss how social media reputation and influence marketing can be used to benefit your business. See the full agenda here.