Today's post, The Error of Crowds was originally published on April 1, 2007. A summary (from the LW wiki):

Mean squared error drops when we average our predictions, but only because it uses a convex loss function. If you faced a concave loss function, you wouldn't isolate yourself from others, which casts doubt on the relevance of Jensen's inequality for rational communication. The process of sharing thoughts and arguing differences is not like taking averages.

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