What’s a vote worth?

By Paul Walker 17/11/2012

A question asked by John Gibson in a column at VoxEU.org. He notes that even before the turmoil of Hurricane Sandy, many Americans were considering not bothering to register a vote for their next president. By looking at the costs and benefits of voting, this column argues that not voting may actually be the rational choice.

Why bother voting? The probability of casting the deciding ballot is infinitesimally small in national elections. Hence, the cost of voting normally exceeds any plausible value of expected benefits from the preferred candidate winning.

It is highly unlikely that the benefits for a voter from any politician’s platform are going to be large enough to counter the cost of voting. Thus if voting is rational it comes down to a comparison of the costs with the consumption benefits. But if these costs and benefits are small, the decision to vote is sensitive to small variations in either term. If these small effects are hard to measure, individual voter turnout will seem largely random and random voting presents a seemingly difficult challenge for the rational voter model.

Gibson offers some new research on the opportunity cost of voting.

Along with my collaborators, I have recently reported results in Public Choice […] with very precise measures of the opportunity cost of voting. To calculate these costs we cross-referenced individual voter turnout in a general election from New Zealand with GIS estimates of the road distance from residential areas to the nearest polling station. By combining travel time estimates from Google Maps with estimated wages for the survey respondents, we obtained a detailed measure of the opportunity cost of time spent travelling to and from the polling station.

Our results show that even very small costs may deter voter turnout. Each extra kilometre – or two minutes’ driving time – to the nearest polling booth reduces turnout by one percentage point, all else the same. These effects are robust to various sources of confounding, including endogenous sorting of residential location, measurement error, and non-linearities. These results support one implication of rational voter theory […] that “if the B (benefits) or PB (benefits weighted by the probability that a person’s vote matters) term is indeed quite small, then a small increase in the cost of voting – such as driving a mile instead of a half-mile to the polls – would significantly reduce turnout.”

Non-nested testing shows that using our new measure of the opportunity cost of time spent voting, formed by combining estimated travel time with imputed wages, outperforms simpler distance-based measures of costs. We find that small increases in the opportunity costs of time can have large effects in reducing voter turnout. For example, at an opportunity cost of NZ$10 (equivalent to US$8) the predicted national turnout would be just 75%, which is down seven percentage points from the mean. In urban areas, predicted turnout falls even more sharply with respect to opportunity costs.

While the external validity of findings from New Zealand would typically be limited, a number of features of this setting allow for especially clean estimates of the impacts of opportunity costs on turnout.

  • First, the general election voting is on a Saturday and almost always in person, so it is reasonable to assume that people are travelling from their home (the locations of which we use in the GIS algorithm).
  • Second, registering to vote is compulsory, while voting is not, so there is no two-stage decision to model of whether first to register and then to vote.
  • Third, our measure of individual turnout comes from an electoral survey which is validated by checking against the electoral rolls, so there is no over-reporting of voting as often happens with other surveys.
  • Finally, this is a setting with ample polling places per voter, little road congestion, little use of absentee ballots, and no state/provincial governments, upper house, or an elected executive or judiciary.

Hence, the triennial election for national parliament is the only politically important election in New Zealand, as well as the only one that involves in-person voting.

Showing that small opportunity costs of voting matter for voter turnout even in this setting extends and corroborates the findings of the previous, more spatially limited, case studies in the political science literature. An important implication follows from finding that opportunity costs are low, but that turnout is still sensitive to those low costs. If these low costs were not able to be accurately measured (as has typically been the case previously), then the decision to vote would (erroneously) appear largely to be random.

So all of us who choose not to vote in elections are, as we have always thought, making a rational decision.