Ah - so that is one possible explanation. The poll relies on the number of times a coaster beats another compared coaster in that category, whether the category all is all, woo does or steel. I guess I can see how that would work, although it still makes me wonder whether it can accurately assess the true mean feeling of the respondents. When the categories have been only either wood or steel, it makes more sense - but when you mix them up, it becomes a bit nebulous.