Voter turnout

 ( Turning ) 

Ballots Cast: Total number of ballots cast, regardless of how many were filled-out or accepted.

Ballots Accepted: this subtracts but in some places includes blank ballots that were otherwise accepted.

Completed Ballots: This metric looks at ballots that were accepted and completed. This is the smallest numerator, but captures only those ballots that will impact the outcome of the election.

For the numerator, it is often assumed that the number of voters who went to the polls should equal the number of ballots cast, which in turn should equal the number of votes counted, but this is not the case. Not all voters who arrive at the polls necessarily cast ballots. Some may be turned away because they are ineligible, some may be turned away improperly, and some who sign the voting register may not actually cast ballots. Furthermore, voters who do cast ballots may abstain, deliberately voting for nobody, or they may spoiled ballot their votes, either accidentally or as an act of protest.

In the United Kingdom, the Electoral Commission distinguishes between "valid vote turnout", which excludes spoilt ballots, and "ballot box turnout", which does not.

In the United States, it has been common to report turnout as the sum of votes for the top race on the ballot, because not all jurisdictions report the actual number of people who went to the polls nor the number of undervotes or overvotes.Kimball W. Brace, Overview of Voting Equipment Usage in United States, Direct Recording Electronic (DRE) Voting , statement to the Election Assistance Commission, May 5, 2004. Overvote rates of around 0.3 percent are typical of well-run elections, but in Gadsden County Florida, the overvote rate was 11 percent in November 2000.Douglas W. Jones, Human Factors in Voting Technology , presentation to the Council on Governmental Ethics Laws September 29, 2002, Ottawa Canada.

Voting-age population: everyone above the legal voting age in a country regardless of citizenship status or other factors that might affect voting eligibility. This has the advantage of being easier to measure than 'eligible voters.'

Eligible voters: This measures all the voters allowed to vote under current law, which in some places includes people who have not registered or re-registered to vote. This is more difficult to measure as more categories of people are disenfranchised and can include non-resident voters.

Registered voters: This measurement captures all who are registered to vote. This has the advantage of being easy to measure and readily accessible, though overlooks those who are unwilling or unable to register due to barriers such as a complex registration or re-registration process.

In the United States, for example, there is no accurate registry of exactly who is eligible to vote, since only about 70–75% of people choose to register themselves.Katz p. 239 Thus, turnout has to be calculated based on population estimates. Some political scientists have argued that these measures do not properly account for the large number of Green card (green card holders), undocumented immigrants, disenfranchised felons and persons who are considered 'mentally incompetent' in the United States. Voter turnout everywhere would be higher if measured by eligibility and not voting-age population.Niemi and Weisberg "Introduction." Controversies in Voting Behavior. p. 25

Even in countries with fewer restrictions on the franchise, voting age population turnout data can still be impacted by large numbers of non-citizen residents and non-resident citizens voting, often under-reporting turnout by as much as 10 percentage points. Professor Michael P. McDonald constructed an estimation of the turnout against the 'Suffrage' (VEP), instead of the 'voting age population' (VAP). For the American presidential elections of 2004, turnout could then be expressed as 60.32% of voting eligible population, rather than 55.27% of voting age population.McDonald "2004 Voting-Age and Voting-Eligible Population Estimates and Voter Turnout"

In New Zealand, registration is supposed to be universal. This does not eliminate uncertainty in the eligible population because this system has been shown to be unreliable, with a large number of eligible but unregistered citizens creating inflated turnout figures.Katz p. 334

For some time, the Gallup Organization has utilized a metric of polls to determine who would vote. These polls would look at "intention to vote, registration status, reported frequency of past voting, awareness of where to vote, interest in politics in general, interest in the particular election, and intensity of candidate preference."Asher, H. B. (2017). Polling and the public: What every citizen should know. CQ Press, an imprint of SAGE Publications.

Since around 1985, there appears to be a gradual decrease in voter turnout globally when looking at the voting-age population.

A country with a highly efficient registration process is France. At the age of eighteen, all youth are automatically registered. Only new residents and citizens who have moved are responsible for bearing the costs and inconvenience of updating their registration. Similarly, in Nordic countries, all citizens and residents are included in the official population register, which is simultaneously a tax list, voter registration, and membership in the universal health system. Residents are required by law to report any change of address to the register within a short time after moving. This is also the system in Germany (but without the membership in the health system). Spain has also a similar system called "Padrón Municipal de Habitantes", held by municipalities. Persons register themselves in the Padrón as local residents (every resident in Spain must be registered in any municipality). The Padrón is used for providing most local, regional, and national government services. It also serves as the electoral register. In order to avoid duplications and to gather statistics on demography, the Padrón is supervised by a national government agency, the Instituto National de Estatística (INE). La Oficina Electoral del Censo is the bureau, as part of the INE, responsible for compiling the electoral roll. Every Spanish citizen or EU resident, older than 18 years, is automatically included in the voter register.

Penalties for failing to vote are not always strictly enforced, and sanctions for non-voters are often mild. For instance, while voting is nominally compulsory in Greece for adults up to 70 years of age, no one has ever been prosecuted for failing to vote, with voter turnout rates reaching as low as 57% in the September 2015 Greek legislative election. In Australia, people who do not vote are subject to a small fine, which is easily waived if one of many acceptable excuses for failing to vote is provided. In Bolivia, however, if a voter fails to participate in an election, they may be denied withdrawal of their salary from the bank for three months. The Guardian Compulsory voting around the world

A 2017 experimental study found that by sending registered voters between the ages of 18 and 30 a voter guide containing salient information about candidates in an upcoming election (a list of candidate endorsements and the candidates' policy positions on five issues in the campaign) increased turnout by 0.9 points. Voting advice applications have strong evidence to increase voter turnout and vote choice and moderate evidence to increase voting knowledge.

A 2018 study found that "young people who pledge to vote are more likely to turn out than those who are contacted using standard Get-Out-the-Vote materials. Overall, pledging to vote increased voter turnout by 3.7 points among all subjects and 5.6 points for people who had never voted before."

The basic formula for determining whether someone will vote, on the questionable assumption that people act completely rationally, isThe basic idea behind this formula was developed by Anthony Downs in An Economic Theory of Democracy. published in 1957. The formula itself was developed by William H. Riker and Peter Ordeshook and published in

$PB\; +\; D\; >\; C,$

where

• P is the probability that an individual's vote will affect the outcome of an election,
• B is the perceived benefit that would be received if that person's favored political party or candidate were elected,
• D originally stood for democracy or civic duty, but today represents any social or personal Utility an individual gets from voting, and
• C is the time, effort, and financial cost involved in voting.

Since P is virtually zero in most elections, PB may be also near zero, and D is thus the most important element in motivating people to vote. For a person to vote, these factors must outweigh C. Experimental political science has found that even when P is likely greater than zero, this term has no effect on voter turnout. Enos and Fowler (2014) conducted a field experiment that exploits the rare opportunity of a tied election for major political office. Informing citizens that the special election to break the tie will be close (meaning a high P term) has little mobilizing effect on voter turnout.

Riker and Ordeshook developed the modern understanding of D. They listed five major forms of gratification that people receive for voting: complying with the social obligation to vote; affirming one's allegiance to the political system; affirming a partisan preference (also known as expressive voting, or voting for a candidate to express support, not to achieve any outcome); affirming one's importance to the political system; and, for those who find politics interesting and entertaining, researching and making a decision.Riker and Ordeshook, 1968 Other political scientists have since added other motivators and questioned some of Riker and Ordeshook's assumptions. All of these concepts are inherently imprecise, making it difficult to discover exactly why people choose to vote.

Recently, several scholars have considered the possibility that B includes not only a personal interest in the outcome, but also a concern for the welfare of others in the society (or at least other members of one's favorite group or party).Aaron Edlin, Andrew Gelman, and Noah Kaplan. 2007. "Voting as a Rational Choice: Why and How People Vote to Improve the Well-Being of Others." Rationality and Society. In particular, experiments in which subject altruism was measured using a dictator game showed that concern for the well-being of others is a major factor in predicting turnoutFowler, James H. "Altruism and Turnout," Journal of Politics 68 (3): 674–683 (August 2006) and political participation.Fowler, James H., Kam CD "Beyond the Self: Altruism, Social Identity, and Political Participation," Journal of Politics 69 (3): 811–825 (August 2007)Loewen, PJ "Antipathy, Affinity, and Political Participation," Canadian Journal of Political Science (Forthcoming 2010) This motivation is distinct from D, because voters must think others benefit from the outcome of the election, not their act of voting in and of itself.

Some view that ethnicity and race have little effect when education and income differences are taken into account.

A 2018 study found that while education did not increase turnout on average, it did raise turnout among individuals from low socioeconomic status households. Occupation has little effect on turnout, with the notable exception of higher voting rates among government employees in many countries.

There can also be regional differences in voter turnout. One issue that arises in continent-spanning nations, such as Australia, Canada, the United States and Russia, is that of . Canada banned the broadcasting of election results in any region where the polls have not yet closed; this ban was upheld by the Supreme Court of Canada.

An example is the 2004 U.S. presidential election. With an intensely polarized electorate and all polls showing a close finish between President George W. Bush and Democratic challenger John F. Kerry, the turnout in the election was close to 60%, resulting in a record number of popular votes for both candidates (around 62 million for Bush and 59 million for Kerry). However, this race also demonstrates the influence that contentious social issues can have on voter turnout; for example, the voter turnout rate in 1860 wherein anti-slavery candidate Abraham Lincoln won the election was the second-highest on record (81.2 percent, second only to 1876, with 81.8 percent). Nonetheless, there is evidence to support the argument that predictable election results—where one vote is not seen to be able to make a difference—have resulted in lower turnouts, such as Bill Clinton's 1996 re-election (which featured the lowest voter turnout in the United States since 1924), the United Kingdom general election of 2001, and the 2005 Spanish referendum on the European Constitution; all of these elections produced decisive results on a low turnout.

A 2020 NBER paper, examining evidence from Swiss referendums, found that an awareness by the electorate that an election would be close increased turnout. Controlling for canton and vote fixed effects, the study determined "that greater Swiss canton newspaper coverage of close polls significantly increases voter turnout"