Correlation

Mural reads: Letters in winning word of Scripps National Spelling Bee [red] correlates with Number of people killed by venomous spiders [black]. First y-axis [red]: 5, 10, and 15 letters. X-axis: every year 1999-2009. Second y-axis [black]: 0, 5, 10, and 15 deaths.

The mural is funny because it implies that the number of letters in a spelling bee word causes people to be killed by spiders (hence the illuminati eyeball that signifies a conspiracy theory and enlightenment), while really, the correlation is a random coincidence. It is important to remember in the scientific world that correlation does not guarantee causation because sometimes the variables make more sense or are expected to have a causation relationship, but only good experiments can prove causation.