Radiohead launched a brave experiment last month: putting its new album, In Rainbows, online and letting fans decide how much - if anything - they paid to download it.

Now, net traffic tracking giant Comscore says 62% of the UK band's fans chose to pay nothing. And of those who did, $US2.26 was the mean (as opposed to median) price.

Radiohead has hit back, rubbishing Comscore's figures, on RollingStone.com and elsewhere, as "wholly inaccurate and in no way reflect definitive market intelligence or, indeed, the true success of the project" but refusing to provide its own hard numbers - and stating that no third party can know, since the band's site is independently run.

Meanwhile, although Gigwise.com gushed that Radiohead sold 1.2 million copies of In Rainbows, Comscore says, sorry, wrong. According to its numbers, a total of 1.2 million people visited Radiohead's website during October and not all of them downloaded the album. Comscore says it knows how many but won't say for "commercial confidentiality" reasons. The band won't comment.

Enter The Wall Street Journal's "The Numbers Guy" blogger, who points out that Comscore could divine the number of people visiting the band's website and downloading the album. The tracker has an uber panel of 2 million volunteers worldwide, and from their surf logs its extrapolates the behaviour of us all (in a notable local example, Yahoo!xtra has chosen to use Comscore as its main traffic metric, abandoning Nielsen//NetRatings).

Big money in small numbers
But, crucially, Comscore's Andrew Lipsman pointed out to The Numbers Guy that Radiohead doesn't need many paying downloads to make a decent slice of dosh. Since they've cut record labels - or even iTunes - out of the picture, with only 5% of visitors stumping up an average $US2.26, the band would have still scored $US360,000 revenue during October. And Lipsman

That is, of course, if we're talking 5% of 1.2 million people. Again, Radiohead's lips are sealed, and Comscore never, for any site, reveals what actual number of its panellists visited - making it impossible to gauge its margin of error.

Free? Steal it anyway
Another interesting factoid from all this: even though In Dreams was right there on Radiohead's site, for free, Forbes.com reports that 500,000 people downloaded pirate copies from unauthorised sites instead. That's bad news for Radiohead, in that people can also order In Rainbows on disc from its website, so it loses the chance to upsell downloaders to the full-resolution audio splendor of the CD version, due for Dec 31 release (along with a $US80 boxed version that includes a bonus disc and - for irony fans - a vinyl version).