You’re a blogger who, for whatever reason, wishes to remain anonymous. You are careful not to mention anything that could tie the blog to you, and you have gone through the trouble of hiding any personal information that might show on the domain record and made sure other sites (or blogs) you maintain all have different IP addresses.

But if you use the same Google Analytics account for following the statistics about your sites’ visitors, you’re doomed – connecting all your sites to you is an easy-to-do task if you haven’t taken the aforementioned precautions when setting them up and maintaining them.

The fact was discovered by tech entrepreneur Andy Baio, who wanted to discover who was behind a particular blog which was spewing “spittle-flecked rage” at a number of Mac-oriented writers. He managed to do that because the blogger used the same Google Analytics ID for another blog he was keeping – a blog on which he shared his name and photo, information about his family and even named his employer.

As it turns out, the free online services who offer reverse lookup of Google Analytics IDs such as eWhois and Statsie provided simple results that tied the two blogs to the same person because of the shared unique ID.

Shocked a bit about how easy the task has been, he tried the same tactics with 50 random anonymous blogs. Of the 50, 14 use Google Analytics, and 7 share the same ID – which the service requires to be put on every page of the site – with other sites they maintain.

“In about 30 minutes of searching, using only Google and eWhois, I was able to discover the identities of seven of the anonymous or pseudonymous bloggers, and in two cases, their employers,” says Baio. “One blog about Anonymous’ hacking operations could easily be tracked to the founder’s consulting firm, while another tracking Mexican cartels was tied to a second domain with the name and address of a San Diego man.”

“Finding anonymous bloggers from Analytics is less likely than other methods. It’s still more likely that someone would slip up and leave their personal info in their domain or share a server IP than to share a Google Analytics account. But it’s also more accurate,” he points out. “Hundreds or thousands of people can share an IP address on a single server and domain information can be faked, but a shared Google Analytics is solid evidence that both sites are run by the same person.”

He hasn’t, of course, “unmasked” these bloggers – he simply contacted them to notify them of the danger they are in. But given that other people are also unaware of this fact, he decided to go public and offer a number of recommendations for bloggers who wish to remain anonymous.