Last week Netbanker.com touted the traffic results of Mint.com, citing Mint’s 1.1 million visitors in the month as evidence of “soaring” web traffic among online personal finance management sites. Among the sites Netbanker lauded for generating higher traffic last month were Geezeo, Quicken Online, BudgetTracker, and Thrive.

Not so fast there. Despite the temptation to yahoo over Mint’s growth to 1.1 million visitors in January from 890,000 in December 2008, it is important to note that Compete‘s numbers are not absolutely accurate, a fact that the folks at Compete are more than ready to acknowledge.

Compete generates its data by analyzing the web traffic of about 2 million internet users. “Their internet activity is tracked, and then aggregated, enhanced, and normalized to represent the U.S. internet population,” according to Compete.

The problem is that these 2 million people don’t always provide an accurate traffic portrait for less-popular sites. I asked Compete about this and they owned up to the problem in the following reply email to my query: “As with any sample-based system, the further you go down the ‘long tail’ of the internet, the more difficult it becomes to provide an accurate estimate of site analytics, so for [some] sites … these are just rough [traffic] estimates. Another reason the traffic numbers you are seeing may be less than what you expect is because Compete reports analytics for the U.S. internet browser population only, so any international traffic that your site may get is not included.”

What is the demarcation of a site that is officially a part of the “long tail”? I have no idea, which is why I still use Compete (particularly since it is free), but I do so with a slight grain of salt. Netbanker readers, I imagine, should, too.