My comment was upvoted to +12, so it is possible it did indeed have a measurable effect, but considering that's a far larger sample of LW readers, I would tend to say the result is probably more accurate, at least for the set of LW readers. I wish we had better data from the survey on how lurkers differ from posters, at least we have a sort of usable karma distribution for non-zero values.
Here's the news article on this: http://www.yourmorals.org/blog/2011/11/how-to-use-groups-at-yourmorals-org/
And here's the group that the LW community just created: http://www.yourmorals.org/setgraphgroup.php?grp=623d5410f705f6a1f92c83565a3cfffc
I think it will be very interesting to see what we can all get on this.