Group intelligence is multiplicative when idiots are involved - combining a half-wit with another half-wit does not result in a full-witted person, it results in a quarter-witted person (1/2 x 1/2 = 1/4). Combining a full-witted individual with a half-wit still only yields a half-wit. The more of these "wrong kinds of people" you have involved in the process, the worse things get.

- Matt Inman, SEOMoz Blog