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Voting and Habit Formation in the United States
Last registered on November 25, 2016


Trial Information
General Information
Voting and Habit Formation in the United States
Initial registration date
November 25, 2016
Last updated
November 25, 2016 9:09 PM EST
Primary Investigator
Columbia University
Other Primary Investigator(s)
PI Affiliation
Tel Aviv University
PI Affiliation
Yale University
Additional Trial Information
Start date
End date
Secondary IDs
Habit is a frequently mentioned but understudied cause of political action. This article provides the first direct test of the hypothesis that casting a ballot in one election increases one's propensity to go to the polls in the future. A field experiment involving tens of thousands of registered voters was conducted prior to the November general election of 1998. Subjects were randomly assigned to treatment conditions in which they were urged to vote through direct mail or face-to-face canvassing. Compared to a control group that received no contact, the treatment groups were significantly more likely to vote in 1998. The treatment groups were also significantly more likely to vote in local elections held in November of 1999. After deriving a statistical estimator to isolate the effect of habit, we find that, ceteris paribus, voting in one election substantially increases the likelihood of voting in the future. Indeed, the influence of past voting exceeds the effects of age and education reported in previous studies.
External Link(s)
Registration Citation
Gerber, Alan, Donald Green and Ron Shachar. 2016. "Voting and Habit Formation in the United States." AEA RCT Registry. November 25. https://doi.org/10.1257/rct.1666-1.0.
Former Citation
Gerber, Alan et al. 2016. "Voting and Habit Formation in the United States." AEA RCT Registry. November 25. http://www.socialscienceregistry.org/trials/1666/history/12019.
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Experimental Details
Personal Canvassing - During each Saturday and Sunday for four weeks prior to the 1998 election, canvassers were sent to contact randomly selected registered voters. Canvassers appealed either to the citizen's sense of civic duty, neighborhood solidarity, or desire to cast a pivotal vote. Additionally, ordinarily canvassers close their appeal by saying, "We hope you'll come out and vote." For a random subset of the treatment group, the closing statement was augmented with the question, "Can I count on you to vote on November 3rd?"

Direct Mailings - The direct mail treatment group was separated into three subgroups and sent 1, 2, or 3 mailings, respectively. The mailings were sent out at three points in time: 15 days before the election, 13 days before the election, and 8 days before the election. The subgroup that was sent three pieces of mail was included on all three mailing dates; the subgroup receiving two mailings was sent mail on the two mailing dates closest to the election, and the remaining subgroup was sent mail eight days before election day.

Please refer to Gerber & Green (2000) for more details about the mail and canvassing interventions.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Voter turnout in 1998 and 1999
Primary Outcomes (explanation)
Voter turnout was measured using public records for both the 1998 and 1999 elections.
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
The experiment was designed to measure the effect of personal canvassing and direct mail appeals on voter turnout. The experiment was a 2 x 4 design whereby individuals were assigned to receive canvassing (or not), and between 0-3 separate mailings.
Experimental Design Details
Randomization Method
The sample was divided by a series of independent random assignments. Random assignment was conducted via computer software (SPSS).
Randomization Unit
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
25,200 individuals were analyzed -- in the published study, no correction was made, unfortunately, for the fact that some voters lived in two-person households.

See Gerber and Green (APSR 2005) for a comparison of corrected and uncorrected standard errors for the original 1998 turnout analysis.
Sample size: planned number of observations
25,200 individuals
Sample size (or number of clusters) by treatment arms
No canvassing + no mail: 10,073 individuals
No canvassing + 1 mail: 3,309 individuals
No canvassing + 2 mails: 3,515 individuals
No canvassing + 3 mails: 3,353 individuals
Canvassing + no mail: 2,492 individuals
Canvassing + 1 mail: 778 individuals
Canvassing + 2 mails: 826 individuals
Canvassing + 3 mails: 854 individuals
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB Name
IRB Approval Date
IRB Approval Number
Post Trial Information
Study Withdrawal
Is the intervention completed?
Intervention Completion Date
October 26, 1998, 12:00 AM +00:00
Is data collection complete?
Data Collection Completion Date
November 03, 1999, 12:00 AM +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
25,200 individuals
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
25,200 individuals
Final Sample Size (or Number of Clusters) by Treatment Arms
Final sample size differed from planned sample size for the canvassing treatment. 4,950 individuals were assigned the canvassing treatment, but canvassers were only able to contact 1,462 of the 4,950 (29.5%) individuals.
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)
A field experiment assessed the effects of a nonpartisan voter mobilization drive. On the weekend before the 1998 general election, voters in the treatment group received an 8" x 11" card on which was printed a nonpartisan encouragement to vote. This treatment had no effect on the turnout rates of registered Republicans and Democrats, but it increased the turnout of those voters unaffiliated with a major party by approximately 7%. We find that the treatment was particularly effective at increasing voting among those unaffiliated voters who voted in 1996.
Gerber, Alan S., and Donald P. Green. 2000. "The Effect of a Nonpartisan Get-Out-the-Vote Drive: An Experimental Study of Leafletting." The Journal of Politics 62 (3): 846-857.
Voting May Be Habit-Forming: Evidence from a Randomized Field Experiment
Gerber, Alan S., Donald P. Green, and Ron Shachar. 2003. "Voting May Be Habit-Forming: Evidence from a Randomized Field Experiment." American Journal of Political Science 47(3): 540-550.