There’s a good story at 538.com by Nathaniel Rakich on the turnout effects of automatic voter registration. He does a good job identifying the boundaries of the potential effects, and is sensitive to the difficult problem of identifying the counter-factual.
Gronke quote about behavioral economics and opt-in / opt-out implementation:
And then there’s the behavioral economics of it all. Reed College professor Paul Gronke told FiveThirtyEight that social science research has generally found that an opt-out system (like AVR) is more effective than an opt-in one (like having to actively register yourself).
The research continues!