Americans have some astonishing misconceptions about international affairs.

As the Washington Post's Dylan Matthews explained last month, the baffling fact that 15 per cent of Ohio Republicans believe Mitt Romney deserves more credit than Barack Obama for killing Osama bin Laden may have as much to do with polling psychology and sampling error as with self-delusion or ignorance. But here are some other statistics that may surprise you:

* 41 per cent of Americans believe China is the world's leading economic power, according to a 2012 Pew poll (the correct answer is the United States, which 40 percent of respondents in the Pew poll selected).

* 73 per cent of Americans could not identify communism as America's main concern during the Cold War, according to Newsweek, which administered an official citizenship test in 2011.

* 9 per cent of Americans frequently worry about becoming victims of terrorism, according to a 2011 AP-GfK poll (Reason magazine has calculated that the chances of being killed by a terrorist are roughly one in 20 million, and that "in the last five years you were four times more likely to be struck by lightning than killed by a terrorist").

* Nearly 25 per cent of Americans don't know that the United States declared its independence from Great Britain, according to a 2011 Marist poll.

* 71 per cent of Americans believe Iran already has nuclear weapons, according to a 2010 CNN/Opinion Research Corporation poll (Israel, the United States, and the International Atomic Energy Agency would beg to differ).

* The average American thinks that the United States spends 27 per cent of the federal budget on foreign aid, according to a 2010 World Public Opinion poll (the figure is more like 1 percent).

* 33 per cent of Americans believed Saddam Hussein was personally involved in 9/11 as late as 2007, according to a CBS News/New York Times poll (it's worth noting that the number was down from 53 per cent in 2003, and that more recent polls suggest the percentage has continued to decline since 2007).

* 88 per cent of young Americans couldn't find Afghanistan on a map, 75 per cent couldn't locate Iran or Israel, and 63 per cent couldn't identify Iraq, according to a 2006 Roper Public Affairs/National Geographic Society poll.