Yesterday, KissMetric came out with one those fancy infographics. This one about Quora.

It is a nice looking infographics but with a huge problem. The numbers behind the "Quora Growth Metrics" are from Compete, a completely unreliable source of data.

KISSmetric note that "This graph is based on speculative data from compete.com, not definite numbers from Quora." Speculative being the keyword here.

Compete is not a trustworthy source of information. I am surprised by the number of sites who keeps using them without questioning the data. All it takes, is for you to compare your own site, with what Compete reports.

Here is an example from this site. The yellow line shows the absolute unique visitors reported by Google Analytics (which I use). The blue one is Compete.

As you can see, Compete is all over the place. Some days it is only 5% off, but the next day it is 57% off. In July, Compete even claimed that I had 16% *more* traffic than what I actually had. And in 2011 it has not even been close to the actual numbers.

Compete fluctuates between being 5%-73% wrong.

The only one worse than Compete is Quantcast. It is just useless. Quantcast is consistently 89%-99% wrong. This is a problem with pretty much every 3rd party source.

You might think this is not a big deal, but it does have a negative impact on where companies place their ads.

One example, Google's Ad Planner reports that I have 70,000 unique visitors, but that is only 10% of the actual traffic. When people use that service to check up on this site, they get the wrong picture. As a result, I do not sell the ad spot.

Note: Earlier today, I allowed Google Ad Planner to access to my actual data, but it will take 48 hours before you might see any change.

The only service out there, providing any form of useful data, is Alexa. It doesn't give any specific numbers, only vague percentages, but the pattern is spot on. Here I have superimposed the graph from Google Analytics (in green) with the one from Alexa (blue).

The point is that marketing people, news sites, and journalists must stop using data from these sources. They are inaccurate, causing more harm than good.

You are better off not knowing, than to rely on wildly misleading data. And if you are a journalist or a media site? Don't mislead your readers.

Read also:

"Reddit: We Have More Traffic Than You Think" - Quantcast, Compete and Nielson reported 1 million visitors, Reddit actually has 8 million.

"Real Social Data, Please!" - debunking another analytic analysis based on inaccurate data.