Accuracy of RCP average for Democratic Primary

I've seen that 7% number bandied about but can't find the work behind it.

Here's what I get:



Unless I've done something wrong, this tells us Obama polled on average 2.33 percent lower than he performed.

I've left out Michigan and Florida which were just too goofy to put any stock in the results. I also rounded the vote percentages for most of the states the nearest percentage, but that shouldn't matter much.

Here are RCP averages.

Update: That RCP link above doesn't show Alabama or Connecticut for some reason. But they are here and here, respectively.

Also, I revised the chart with percentages accurate to the tenth and ended up with an average error of 1.99 (i.e. Obama polled 1.99 percent lower than his results):