During election season, we see poll after poll taken by various groups that sometimes hit the mark, more or less, and sometimes are just plain wrong. Maarten Lambrechts produced an interactive graphic called Rock ’n Poll that explains why polls don’t line up with real-world results. Click the check button to advance the graphic. Through the simulation, we take political preference polls in the fictional country of PollLand, which has a million voting citizens, represented by a thousand dots, and eight political parties, each represented by a bright color.
The exercise illustrates the margin of error in imaginary polls in which sampling is perfectly representative and everyone cooperates and tells the truth. If errors creep into polls in PollLand, you can imagine how hard it is to get correct results in the real world. -via Flowing Data