More evidence of just how sophisticated and effective the Obama campaign was online. I love the emphasis on A/B testing.

The appeals were the product of rigorous experimentation by a large team of analysts. “We did extensive A-B testing not just on the subject lines and the amount of money we would ask people for,” says Amelia Showalter, director of digital analytics, “but on the messages themselves and even the formatting.” The campaign would test multiple drafts and subject lines—often as many as 18 variations—before picking a winner to blast out to tens of millions of subscribers. “When we saw something that really moved the dial, we would adopt it,” says Toby Fallsgraff, the campaign’s e-mail director, who oversaw a staff of 20 writers.