This has come up before. Then, it looked like gwern and I both got a boost from name recognition, but for everyone else it was just dependent on when they took the survey.

If I come by every day and upvote everyone, before I come that day a fraction of the people will have upvotes from me and another fraction won't, determined by time. Now add a bunch of people doing similar things but at different schedules (or only upvoting everyone who took it before they did, and not anyone who took it after, because they don't come back to this page).