Does voting by mail make for better choices? A 2020 election study suggests it might

Casting a ballot from home might do more than offer convenience; it could also help citizens select leaders who genuinely reflect their personal political beliefs. A study published in Political Behavior indicates that Americans who voted by mail during the 2020 presidential election were more likely to vote for the candidate who best aligned with their stated views than those who cast ballots in person. The findings suggest that having the flexibility to review ballot choices at home may improve the quality of democratic decision-making.

What does it mean to vote correctly? In political science, the term does not mean choosing the objectively best leader or backing the winning candidate. Instead, it refers to whether a citizen votes for the candidate who best matches their own expressed preferences on policy issues, partisan identity, and assessments of character. When a voter picks a candidate who is a weaker match for their own stated preferences than another candidate on the ballot, researchers call that an incorrect vote.

The research was conducted by Jennifer Wolak, a professor of political science at Michigan State University, and Carey E. Stapleton, a lecturer in the Department of Analytics and Computational Social Science at the University of Massachusetts, Amherst. They examined how different voting environments shape these electoral decisions.

At a traditional polling place, citizens often wait in line and then typically spend three to four minutes completing a lengthy ballot. The authors argue that because many voters are reluctant to hold up others waiting behind them, they rely largely on memory to recall where each contender stands across multiple offices.

Mail-in ballots, by contrast, can be completed at a kitchen table, and voters report taking about two days on average to fill them out. The authors propose that this extra time lets people look up unfamiliar candidates, read through ballot measures, or talk over choices with family members, which may help them make more considered choices.

“With the pandemic, a lot of people voted by mail for the first time,” lead author Wolak told PsyPost. “Filling out your ballot at home is often a different experience than casting your ballot at a polling place. You can take your time when filling out your ballot at home, without worrying about holding up the line or being late to your next appointment.”

“When you are uncertain about how to vote or unfamiliar with a certain electoral race or ballot question, you can do additional research prior to casting your official ballot,” she explained. “Our suspicion was that under these conditions, people might be better able to identify which candidates are aligned with their political goals.”

Research on political knowledge highlights how access to information shapes voter decision-making. For example, a 2019 study suggested that the ability to look things up online may partly stand in for political knowledge stored in memory, particularly among younger Americans who grew up with the internet. Having the ability to look up candidates while filling out a ballot at home may help offset gaps in memory.

At the same time, convenience voting can introduce its own complications. In a 2011 study of California’s 2008 presidential primary, researchers found that precincts with more mail voting gave more votes to candidates who had already dropped out, since mail voters often decided before late-breaking campaign developments. That finding suggests voting from home carries potential drawbacks as well as benefits.

Researchers have also noted that people who take advantage of flexible voting options often differ from those who vote at a polling place. Specifically, a 2020 study suggested that individuals who already possess high political knowledge are more likely to seek out convenience voting methods in the first place. In the 2020 election, mail voters tended to be older, more educated, more liberal, and more knowledgeable, making it necessary to separate the method of voting from these personal traits.

To evaluate whether mail balloting helps voters make better choices, the authors analyzed data from the 2020 American National Election Studies. This extensive survey asked participants about their issue preferences, partisan loyalty, and opinions about candidate traits. The authors combined these responses with official state voter records, which allowed them to verify the exact method each participant used to cast their ballot.

To determine whether someone voted correctly, the researchers used a widely used measure developed by political scientists Richard Lau and David Redlawsk. It scores how well each presidential candidate matched a respondent’s own answers on partisanship, policy issues, evaluations of the incumbent’s performance, perceptions of the candidates’ traits, and ties to social groups associated with each party. A participant who chose the candidate with the higher score was coded as voting correctly.

The authors first tested this relationship using a statistical model of 4,728 voters while holding several background factors constant. The model accounted for political interest, strength of party affiliation, political knowledge, education, ideology, age, gender, race, and ethnicity. The authors also included a measure of in-person early voting to see if voting before Election Day carried similar benefits.

The results indicated that casting a ballot by mail was associated with an estimated 2.6 percentage point increase in the probability of voting correctly. In baseline terms, roughly 90 percent of in-person voters selected the candidate aligned with their preferences, compared to nearly 93 percent of mail voters, a gap roughly equivalent to the boost associated with a one-standard-deviation increase in political knowledge. In contrast, the difference in correct voting between in-person early voters and Election Day voters was not statistically significant, suggesting that the advantage was tied to voting at home rather than to voting early.

To ensure that this pattern was not simply the result of differences in who chooses to vote by mail, the authors used statistical matching procedures. One method, known as coarsened exact matching, paired mail voters with in-person voters who fell into the same broad ranges on key traits. Across three versions, which matched on political factors such as interest and knowledge, on demographics, or on both, voting by mail remained associated with an estimated gain of roughly 2.1 to 4.7 percentage points in correct voting, with sample sizes ranging from 523 to 4,907.

The authors also applied entropy balancing, an analytical technique that reweights the data so that mail voters and in-person voters look alike on many characteristics without discarding participants. Balancing on the same factors used in the earlier models produced an estimated 2.7 percentage point gain among 4,728 voters, and adding measures such as concern about the election outcome, belief in one’s ability to influence politics, ideological consistency, and past voting produced a 1.7-point gain among 4,658 voters. In an expanded model of 4,634 voters that also balanced on state-level factors, such as campaign competitiveness and the ease of voting by mail, the estimated boost was 5.0 percentage points.

The authors then evaluated how state election laws influenced these outcomes across 4,658 voters using a mediation analysis. In 2020, states took very different approaches to mail voting: nine states and the District of Columbia mailed ballots directly to all registered voters, while other states required specific excuses or notarized documents to cast an absentee ballot. Voters living in states that mailed ballots automatically had a 92 percent predicted probability of voting by mail, compared to only 38 percent in states without universal ballot distribution.

The mediation analysis suggested that state policies making mail-in ballots easier to obtain were indirectly linked to more correct voting by encouraging more residents to vote by mail. This indirect pathway was associated with an estimated increase of about 1.3 to 1.6 percentage points in correct presidential votes. However, the overall difference in correct voting between states with easier and harder access to mail ballots was close to zero, because the indirect boost was offset by a small direct association in the opposite direction that was not statistically significant.

The authors conducted additional analyses to see if the link between mail voting and correct voting existed outside the unusual conditions of the 2020 pandemic. By examining a panel of participants surveyed in both 2016 and 2020, they found that voters who switched from in-person voting in 2016 to mail-in voting in 2020 were more likely to vote correctly in 2020. An analysis of respondents from the 2016 election who were re-surveyed in 2020 indicated that voting by mail was associated with roughly a 5 percentage point gain in correct voting after balancing for demographic and political traits.

“A lot of the discussion around encouraging vote-by-mail has been about increasing participation,” Wolak noted. “Most research has found that introducing vote-by-mail can boost voter turnout, especially among some of the groups who are the least likely to vote.”

“Our work shows an even wider set of civic rewards for vote-by-mail,” she added. “Giving people the opportunity to complete their ballot at home not only increases their likelihood of participating, but it also can increase the odds that they choose the candidates that best match up to their political preferences.”

There are a few things to keep in mind when interpreting these findings. Because the study relied on survey and voting records rather than an experiment where people were randomly assigned to vote by mail or in person, the authors cannot establish direct cause and effect. Although the statistical models accounted for education, political knowledge, and numerous other traits, unmeasured personal factors might still influence both the decision to vote by mail and candidate choice.

Another factor to consider is the modest size of the observed effect, which ranged between two and five percentage points across the various models. In presidential elections, voters already encounter an abundance of news coverage and campaign advertising, which helps roughly 80 to 90 percent of citizens vote correctly regardless of how they cast their ballots. As a result, the room for measurable improvement in presidential contests is relatively small.

“We estimate that compared to those who vote in-person, people who vote by mail are about two percentage points more likely to select the presidential candidate that best lines up with their political preferences,” Wolak pointed out. “It’s a small effect, but we would expect the improvements in the quality of voter decision-making to be even greater in down-ballot races where people have less knowledge about the candidates.”

The authors also emphasized that their research focused on the presidential race because reliable survey measures comparing voter preferences to candidate positions are rarely available for congressional or gubernatorial contenders. In lower-profile contests where campaigns receive less attention, voters typically have far less information stored in memory. Future studies could investigate whether having a ballot at home leads to even larger gains in these less publicized races, where having extra time to look up candidates online might matter most.

The study, “The Effects of Voting by Mail on Correct Voting,” was authored by Jennifer Wolak and Carey E. Stapleton.