The U.S. economy does better under the Republicans. Or under the Democrats. Choose your variables and get either result! This is a fantastic article on recent issues with scientific method, with an interactive visualization that demonstrates p-hacking. I've never seen anything like this before.
http://fivethirtyeight.com/features/science-isnt-broken/
Really cool, it would be interesting to include variable time frames studied and different statistical methods to highlight how these choices can determine results.