The Hunt for Campaign Effects III

Oct 5 '09


In an earlier post, I noted some initial findings from Democratic groups, particularly Catalist, who were doing voter contact, registration, and mobilization in 2008. Today, Marc Ambinder describes a new report from Catalist with the following conclusions (in his words):

bq. According to the analysis, those registered voters contacted by Catalist member groups turned out at a rate of 74.6%; the voters who weren’t turned out in proportions roughly equivalent to the national average — about 60.4%. In four states, the number of new votes cast by liberals exceeded Obama’s victory margin: in Ohio, Florida, Indiana in North Carolina. If you assume that only 60% of these voters chose Obama, the margin was still greater than Obama’s in North Carolina and Indiana, both essential to his victory. With the caveat that correlation does not equal causation, the report provides convincing, if not absolute, evidence that the progressive/Democratic data-mining and targeting operation measurably helped elect Barack Obama.

In a subsequent post, he links to the actual report (.doc). I’ve only skimmed the report, but here are two preliminary conclusions, both noted by Ambinder and Catalist. First, these data are based on correlations between voter contact and political participation. Correlations are not causality, but that doesn’t mean that they are useless. Particularly in light of the next point.

Second, these correlations line up very nicely with some political science evidence. Ambinder and Catalist note, apropos of the graph above (Figure 14 in the report), that in-person contacts seem more effective than phone calls and direct mail in increasing turnout. This is in line with Don Green and Alan Gerber’s work, as well as that of some other scholars.

But Catalist’s findings are eerily similar to another finding from political science research on voter mobilization. Consider the shape of the curves in the graph above. These show that the effect of mobilization efforts was greatest among those with a moderate propensity to vote. Those with a very low or very high propensity were not much affected — the former presumably because they are hard to mobilize and the latter because they are already very likely to vote.

Compare that graph to one from a recently published paper by David Nickerson and Kevin Arceneaux who analyze a set of 11 voter mobilization field experiments conducted from 1998-2003 to determine _who_ is mobilized.


The y-axis — labeled “attempt-to-treat effect” — captures the same thing as the Catalist graph: the effect of some mobilization effort on turnout. Note that the shape of their “high salience” curve looks exactly like Catalist’s curve. It peaks a bit below the midpoint of the vote propensity scale, with a longish right tail. This makes considerable sense: the 2008 presidential election was nothing if not highly salient. Note also that the maximum effect they document, about 0.14 (or 14%), is almost exactly the same as the maximum effect in Catalist’s data. These similarities are uncanny. Nickerson and Arceneaux’s theory looks very, very good.

I can’t help but puff out my chest and declare: Yes, political science research can tell us about the real world.