[jacquesm]

Slashdot always had a tendency to discuss stuff without reading the article first, or at all.

So it doesn't drive as much traffic as you might expect, but when your site does get mentioned on /. it gets much more traffic than a HN posting.

Also, there probably is very little overlap between the typical /. covered site and the sites that woopra covers, /. is not really a start-up related site.

If you were to re-run the numbers with all of google analytics covered sites (impossible to get the data, unfortunately) you'd likely get a different picture.

The barrier to entry for a successful HN posting is much lower than it is on /., the volume of 'posted' stories on /. is much lower too.

All in all less surprising than you'd think at first sight.