Individuals eligible to be part of the study were active voters with a permanent address who had registered before 2006. We consider eligible households to be households with between one and three registered voters. We then restricted the study to nine-digit zip codes containing at least two households with two eligible individuals and somewhere between 3 and 15 total households. We mailed postcards only to those residents who had been eligible to participate in both the 2006 and 2008 spring elections.
We first conducted a randomization based upon each zip code. From the eligible zip codes, we selected a two-voter household at random, which we will call the core household. We then chose 25% of core households to be assigned to control, and 75% were assigned to treatment. For zip codes where core households were assigned to control, all other households in their zip code were also assigned to control. For zip codes where core households were assigned to treatment, zip codes were assigned with equal (1/3) probability into three conditions: First, treatment core households were assigned to be the only household in their zip code receiving treatment. Second, half of the other households in the zip code of the core treatment household were assigned to treatment. Third, all households in the zip code of the treatment core household were also assigned to treatment. Within households assigned to treatment, we randomly chose exactly one individual to receive treatment.
A mailed postcard reminding voters to do their civic duty and vote in spring elections. This postcard included a reminder about whether or not each individual had participated in the previous spring 2006 and spring 2008 elections.
Official turnout records for each subject