Missing Voters Project Methods
The MVP voting data are from a special supplement to the Current Population Survey, administered each November immediately following the election. In the 2018 MVP reports, we share voting trend data from 2008 to 2018, which incorporates three presidential election years (2008, 2012, and 2016) and three mid-term election years (2010, 2014, and 2018). For all years, citizen population counts and percentages are statistically-weighted estimates derived by the Bureau of the Census from national samples of many thousands of adult respondents (88,749 respondents in 2018).
You can access the original 2018 voting participation data tables published by the Bureau of the Census here. These files are in Microsoft Excel format.
The Technical Documentation for the 2018 Voting and Registration File is a 200+page document which provides detailed information about the Current Population Survey, including statistical sampling, population weighting, variable definitions, and margins of error. You can view and download the PDF file here.
We obtained and analyzed some CPS data for our reports from the IPUMS-CPS clearinghouse at the University of Michigan.
Notes on Race and Hispanic Ethnicity
The categories and labels we use in the Missing Voters Project reports correspond to the categories used by the Bureau of the Census in its official statistics, and by many other government agencies. Respondents were asked their race in a single question, and could report multiple races if they chose. Multiracial persons were included in two or more categories if their second or third race was not White. For example, a person who chose Asian and White as their races was included with Asians only, while a person who chose Asian and Black as their races was included in both of those groups. Most multiracial adults chose White as their second race, and so were included in only one race category.
Hispanic ethnicity was asked in a separate question, and respondents could also indicate their ancestry (e.g. Mexican, Puerto Rican).
Whites include persons who were not Hispanic, and chose White as their only race.
Blacks include persons who chose Black alone, or Black and another race. Nationally, 5.3% of Black citizens were multiracial in 2018, and 5.5% were also Hispanic.
Hispanics include persons of all races, including multiracial persons. In 2018, the ancestry of Hispanic adult citizens was 59.4% Mexican, 12.4% Puerto Rican, 10.7% Dominican, 6.1% South American, 4.7% Cuban, 3.9% Central American, and 2.8% Salvadoran.
Asians and Pacific Islanders include Native Hawaiians, other Pacific Islanders, and Asians. Nationally, 9.2% of Asians and Pacific Islanders were multiracial in 2018, and 5.1% were Hispanic.
American Indians and Alaska Natives include persons who chose these race categories, which do not correspond to tribal membership or affiliation. Multiracial persons are included. Information about specific tribal groups (e.g. Navajo) was not collected in the CPS. Nationally, 43.8% of American Indians and Alaska Natives were multiracial and 25.7% were Hispanic.