1. A quality effort can be expected to increase turnout by 7–10 percentage points. Phone calls from volunteer phone banks can also significantly increase turnout, while mailers, robocalls, and other indirect methods tend to be ineffective (Green & Gerber, 2008 Green, D. P. and Gerber, A. S. 2008. Get out the vote! How to increase voter turnout, 2nd, Washington, DC: Brookings Institution Press.  [Google Scholar]). Recently, researchers have attempted to unpack what makes canvassing more or less effective (Michelson, Bedolla, & McConnell, 2009 Michelson, M. R., Bedolla, L. G. and McConnell, M. 2009. Heeding the call: The effect of targeted two-round phonebanks on voter turnout. Journal of Politics, 71: 1549–1563. [Crossref], [Web of Science ®] , [Google Scholar]; Michelson, García Bedolla, Medina, Sarpolis, & Coera, 2009 Michelson, M. R., Bedolla, L. G., Medina, X., Sarpolis, J. and Loera, S. April 2009. When quality comes knocking: Exploring variation in door-to-door campaign effects, April, Chicago, IL: Paper presented at the annual meeting of the Midwest Political Science Association.  [Google Scholar]).

2. Building on the social-psychological model of participation that came out of The American Voter, the political behavior literature has traditionally looked at individual-level characteristics, such as socioeconomic and civic resources, to explain differences in electoral turnout. Though this literature established that individuals with higher socioeconomic status are more likely to vote, it cannot explain why participation rates have not increased as Americans have become more educated and wealthier. Similarly, rational choice theory, with its emphasis on individual-level calculations of self-interest and utility, has been unable to explain turnout in mass elections (Green & Shapiro, 1994 Green, D. P. and Shapiro, I. 1994. Pathologies of rational choice theory: A critique of applications in political science, New Haven, CT: Yale University Press.  [Google Scholar])

3. in political science the term quasi-experiment is used to refer to any observational study where the manipulation is not randomly assigned (Shadish, Cook, & Campbell, 2002 Shadish, W. R., Cook, T. D. and Campell, D. T. 2002. Experimental and quasi-experimental designs for generalized causal inference, Boston, MA: Houghton Mifflin. [Crossref] , [Google Scholar]). In our analysis, the assignment of local canvassers to particular precincts is haphazard but not random, while the assignment of any canvasser whatsoever to individuals is random.

4. Median family income in South Los Angeles is $29,718, and about 30% of the population lives below the poverty line; 50.9% of the residents have less than a high school education. The area is 55.9% Latino and 38.9% African-American (U.S. Census).

5. Canvassers spent each morning in a training session reviewing the script to ensure conformity, but it is possible that there is important variance in canvasser adherence. For this reason, we include canvasser-specific effects in the results presented in Table 5.

6. Social influence may also have been triggered when voters recognized local canvassers, but we are unable to measure the frequency with which this occurred.

7. New or occasional voters are defined as having participated in fewer than four of the last 10 general elections, based upon the voter turnout and registration records provided by the Los Angeles Registrar Recorder's Office.

8. Balance checks for the randomization can be seen in Table A3 (available from the publisher's online edition of this article), and as randomization was conducted at the household level, all standard errors are clustered by household. Households with more than three registered voters were excluded from the experiment because of concerns that the campaign would only be able to contact a single person within the household.

9. This contact consisted of receiving at least one door-to-door visit, sometimes a second, and often also a doorhanger. A doorhanger is a piece of campaign mail left on the household's front door. We define treatment as having received any campaign contact. During the last week of the campaign, some individuals were randomly assigned to receive a second treatment. Analysis of the marginal effect of the second contact yields no statistically significant effect at traditional levels, and all analysis that follow will simply consider the effect of the individuals receiving any campaign contact. Dropping those individuals who received a second campaign contact does not weaken the results for local canvassing. The existing literature on the effectiveness of doorhangers suggests that they have an extremely small effect on turnout (Gerber & Green, 2000 Gerber, A. and Green, D. P. 2000. The effects of canvassing, telephone calls, and direct mail on voter turnout: A field experiment. American Political Science Review, 94: 653–663. [Crossref], [Web of Science ®] , [Google Scholar]; Green & Gerber, 2008 Green, D. P. and Gerber, A. S. 2008. Get out the vote! How to increase voter turnout, 2nd, Washington, DC: Brookings Institution Press.  [Google Scholar]; Nickerson, 2005 Nickerson, D. 2005. Partisan mobilization using volunteer phone banks and door hangers. Annals of Political and Social Science, 601: 10–27. [Crossref], [Web of Science ®] , [Google Scholar]; Nickerson, Friedrichs, & King, 2006 Nickerson, D. W., Friedrichs, R. D. and King, D. C. 2006. Partisan mobilization campaigns in the field: Results from a statewide turnout experiment in Michigan. Political Research Quarterly, 59: 85–97. [Crossref], [Web of Science ®] , [Google Scholar]).

10. We estimated models calculating the effects of the campaign both with and without covariates, including partisan registration, age, voter history, ethnicity (measured by surname), and gender. Additionally, so as to adjust for the potential of precinct-level variation, we present results from a different specification that incorporates fixed effects for each precinct. Our results are displayed in the in Table A1 (available from the publisher's online edition of this article). There is a statistically significant and positive effect of receiving any contact across all methods of estimation. We include indicators for whether or not the age or gender control variables are missing and then fill in values for age and gender to match those missing spaces. This allows us to directly compare the estimates of any contact across all models. Our results are robust to each specification, and these results yield TOTs ranging from 4.8 to 6.6 percentage points.

11. We also estimate the relationship between the contact rate and local intensity without the outlier (where the share of local contacts was greater than 50%). Excluding the outlier does suggest there is a slight positive relationship. As such, analysis of the effectiveness of the treatment will focus on the TOT estimates, which account for the contact rate. The figure without the outlier is included in Figure A1 (available from the publisher's online edition of this article).

12. We also estimated the power of local canvassing without the outlier (where the share of local contacts was greater than 50%). The strong positive relationship persists. The figure without the outlier is included in Figure A2 (available from the publisher's online edition of this article).

13. Analysis excluding the outlier generates the same result and is included in the lower half of Table 4.

14. We extend this analysis by looking carefully at the 2SLS estimates when separating the data into precincts where there was any local canvassing and precincts where there was none. We present evidence in Table A2 (available from the publisher's online edition of this article) that breaks the data into these two subsets, both with and without the inclusion of control variables. These results again support the finding that canvassing by locals is more effective. The estimated TOT for the subset of local precincts is positive and statistically significant in both models, as described in each column. However, the estimated treatment effect is smaller in the precincts where no local contact occurred and is not different from zero when covariates are included. These regressions provide additional evidence that in fact the success of the campaign we observe is due to the success of local canvassing specifically and not merely face-to-face contact in general

15. These results are further supported when we simplify the analysis and include additional covariates in the appendix in Table A2 (available from the publisher's online edition of this article). While these two different types of analysis ensure that the positive results in Table 5 are not attributable to the contact rate of local canvassers, they do not control for as much variability as Table 5 and thus should not be used to extrapolate the magnitude of the local canvassing effort.