A new study published by the Institute for Prospective Technological Studies (part of the European Commission’s “Joint Research Centre”) asserts that “Internet users do not view illegal downloading as a substitute to legal digital music,” and reports that the authors of the study found “no evidence of digital music sales displacement.”

What’s most ‘impressive’ about this study is that it includes no data whatsoever involving revenue or sales. None.

How did the researchers arrive at their conclusion without actually seeing any sales data? Rather than hitch their conclusions to revenue metrics, Luis Aguiar and Bertin Martens extrapolate their thesis from an in-depth look at click data pertaining to both legal and illegal music-related websites.

“Our approach relies on a novel dataset that enables us to follow a large sample of Internet users and their online behavior in five EU countries during 2011,” the report explains. “For each of the individuals in our sample, we observe both information on demographic characteristics and on the webpages visited during the year. This allows us to identify specific visits on websites related to music consumption, both legal and illegal.”

If you’re thinking that this approach lacks a little something — like, you know, any indication whatsoever of whether the users observed in the data downloaded and/or purchased anything from the sites in question — you’d be quite right about that “limitation” of the data presented in this paper.

“It is important to note that we are only able to observe the number of clicks on a given website and that we do not have a precise description of the individual behavior for each click,” the authors concede. “Rather than measuring actual consumption or purchases, our data therefore gives a measure of the propensity to consume music.”

Don’t fret, though; the authors further assure us that this lack of sales data is not a problem!

“We believe, however, that this is still a good approximation to actual consumption,” the authors state. “We see no specific reason for which an individual would go on a music-consumption website with other purposes than to consume music…. In particular, we do not expect individuals to go window-shopping on legal purchasing websites in order to illegally download after their visit. First, information on specific albums, songs or artists can be found on other music-specific websites, so it is not clear why consumers should use legal purchasing websites for such purposes. Second, we believe information on songs’ prices to be almost perfectly known to consumers before they go on legal purchasing websites, ruling out visits solely related to price information seeking.”

Whether or not you think the assumptions above are reasonable, you have to concede that they are assumptions, and not actual data points, or any sort of data that is subject to confirmation or debunking in the context of this study. What the authors appear to view as a small, almost trifling issue is, realistically, a severe limitation on the usefulness of their data set.

I’m not closed to the idea that many people (perhaps even most people) who pirate music also purchase music, nor do I reject the possibility that some of the highest volume pirates are also among the most frequent purchasers of music — I’d just like to see such theories backed up by something more than non-scientific telephone surveys, or analysis of Internet traffic metrics and user behavior that does not include purchasing behavior.