Interesting research from the American Enterprise Institute (abstract in HTML, full text in PDF): They attempt to measure whether turning out for a political rally makes a difference (causes political change, rather than is merely correlated with it), using rainfall at various events as a randomizing independent variable. They conclude that the rallies do make a difference.
“We show that these political protests and the movements they built affected policymaking and voting behavior as well. Incumbent representatives vote more conservatively following large protests in their district, and a rain-free rally in the district increases the likelihood that a Democratic incumbent retires. Larger protests increase turnout in the 2010 elections, primarily favoring Republican candidates. We ﬁnd evidence of sizable effects. In particular, our baseline estimate shows that every Tea Party protester corresponds to a 14 vote increase in the number of Republican votes. Our most conservative estimate lowers that number to 7. The Tea Party protests therefore seem to cause a shift to the right in terms of policymaking, both directly and through the selection of politicians in elections.”
If the Obama-administration IRS’s targeting of Tea Party groups from 2010 to 2012 is a significant part of why the Tea Party was less effective in 2012 than in 2010, AEI argues that the IRS abuses actually changed the outcome of the election.
Hat tip to Wintery Knight.