This was a great election year, and every political writer in the country was one way or another in the fray. "South Carolina just may go Santorum," they'd say, or "From the turnout at the rallies it looks like Gingrich has a good chance." Columnists, bloggers—they're all trying to understand what's happening pretty much in real time. In this space we've tended less toward specific predictions than to trying to sense what might be unfolding and what it means. But you can make mistakes there, too. So, a quick look at some of the things we got right and wrong in 2012. Bonus lesson at the end.

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Early...