Math at the Polls

I learned something new yesterday. I was mad that I am running this poll on my website -- promoting science! -- and my poll looks mathematically wrong. My categories add up to anywhere from 275 to 300%, depending upon when I view the poll.

So, I was sitting there stewing about this and mentioned to my husband (Itinerant Cryptographer) that you should never trust a poll where the percentages add up to something other than 100%.

He said, "Can you vote for more than one category?"

And I said, "Yeah."

And he said, "Think about it. If the average person votes for two categories, the poll would add up to 200%."

Gee, I never thought about it that way. Polling results only add up to 100% when you can vote for just one of the available options. If you can vote for more than one thing ... you get a bizarre-looking poll like mine!