Online 'sentiment' around the prime-ministerial debates
The prime-ministerial debates have been a fascinating experiment, not just in the way that television can influence an election campaign but in a new way of combining the web and TV to make both a richer experience. One example - to blow the BBC's own trumpet - is this page which allows you to review all the key moments of last night's debate and see a transcript of what was said.
Another innovation has been the way a growing number of people have followed these major events via two screens - a laptop perched on their knees as they sit in front of the television, connecting with social networks to comment live on what they're seeing. This has in turn made possible an industry of what's being called "sentiment analysis", which attempts to understand what has been said online.
We've been asking a firm called Lexalytics to give us instant readouts of Twitter sentiment - last night's chart showed David Cameron and Nick Clegg both attracting roughly equal numbers of positive comments, with Gordon Brown in negative territory.
Other firms have been using similar techniques. Linguamatics, based in Cambridge, says it has used sophisticated text-mining software and linguistic analysis to understand how Twitterers reacted. This chart maps positive tweets for each leader, in relation to each question asked during the debate.
The analysis offers a perhaps puzzling result. Counting positive tweets during the debate, it says Nick Clegg had 37% of them, followed by Gordon Brown with 32% and David Cameron in 31%. That's not a result reflected in polls and other sentiment measurements. My hunch is that the volume of tweets may have been higher for Gordon Brown than David Cameron - and for all those positive ones, there were actually more that were negative.
Another company, Meltwater Buzz, tells me it does a much wider sample of online opinion, looking not just at social-media updates but also at blog comments, newspaper articles and just about all readable web content. It has tracked sentiment throughout the election campaign, and produces results very different from those I've seen elsewhere. For instance, the Meltwater tracker shows Nick Clegg achieving lift-off during the second TV debate, not the first. The explanation offered is that it was then that the satirical #nickcleggsfault craze took off, and this was measured as extremely positive for Mr Clegg. The firm's latest trends show David Cameron forging ahead, following Gordon Brown's "bigoted woman" gaffe and then last night's debate.
Once again, let me stress that the technology of "sentiment analysis" is untested - at least in the political arena - so all these charts and conclusions should be taken with a massive pinch of salt. But some of the practitioners are gearing up for the ultimate test, by trying to predict the election result. A week from now, we will know just how seriously to take this new technique.