Alexa is pretty obviously not a scientific way of measuring site traffic as its sample is limited to those who have the IE only Alexa toolbar, but usually it seems somewhat on target.

For some reason though lately, on SWiK.net and SourceLabs.com, it’s been reporting totally wacky numbers – which I can tell because I have the actual traffic logs.

Here’s the graph of both side by side

You might think from this graph that sourcelabs.com and swik.net draw equal traffic, or that sourcelabs draws just a bit more.

However our internal logs tell a very different story, swik.net is drawing approximately 7 times as much traffic – yet today swik.net appears to be drawing half of the reach of sourcelabs.com.

What’s going on here? An order of magnitude difference? It’s true that swik.net draws an unusually small percentage of IE users, as a third of visitors don’t even use Windows—but even the curve of the graph is totally messed, showing us at a third of our top reach a couple months ago when we have been steadily growing and have never had more traffic than we have had in the past couple weeks.

I wish there were a better source of data than Alexa for open source or Firefox friendly sites :/