• by Wendy Davis , Staff Writer @wendyndavis, September 24, 2012

Facebook once again has launched an initiative that's drawing scrutiny from privacy advocates.

The company's latest project, an analytics alliance with Datalogix, is aimed at determining whether online ads affect people's offline purchases.

Datalogix has amassed a wealth of information about users' offline purchases from loyalty cards, which themselves are often tied to email addresses. Facebook obviously also has a database of its users' email addresses. The two companies are now going to compare enough information to figure out how many users who view particular ads go on to make purchases.

Facebook says that the data will all be aggregated and that no individual's information  will be shared between the companies. If so, that potentially mitigates the privacy concerns -- but only to the extent that the anonymization efforts are likely to work as planned. Advocates say they need more information on that point. "The representations about de-identification are not sufficient unless independently verified," Marc Rotenberg, president of the Electronic Privacy Information Center, tells MediaPost.

He has reason to be wary, given that attempts to anonymize data in the past have failedmiserably.

At the same time, Rotenberg (and other observers) are questioning whether the deal between the companies violates Facebook's recent settlement with the Federal Trade Commission. He tells MediaPost he'd like to see the FTC examine Facebook's arrangement with Datalogix to determine whether the social networking service is violating the settlement, which requires Facebook to obtain users' explicit consent before sharing users' information more broadly than in the past.

Whether Facebook was legally required to get users' opt-in consent isn't yet clear, especially given that Facebook isn't sharing information that users have uploaded -- like photos or status updates -- with Datalogix. Instead, Facebook is sharing data about whether users have been served with particular ads.

Nonetheless, the company is engendering a lot of mistrust by springing this new deal on people without some sort of clear notice. What's more, while users appear able to opt out of the deal, doing so isn't as simple as clicking on a link. Facebook directs users to Datalogix to opt out of its program. Datalogix says on its site that it lets users opt out of analytics, but to do so people must submit a host of personal information to the company.

Of course, users can still resort to self-help, such as by registering for loyalty cards with different email addresses than they provide to Facebook. The company probably doesn't want to see that happen, but is encouraging it by failing to offer members a simpler way to control how data about them is used.