13 reasons why Exit Polls get it wrong sometimes

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An Exit poll, as the name suggests, is a poll taken immediately after voters exit the polling booth. Private companies working for popular newspapers or media organizations conduct these exit polls and are popularly known as pollsters. Once the data is collected, data analysis and estimation is used to predict the winning party and the number of seats captured. Turnout models which are built using logistic regression or random forest techniques are used for prediction of turnouts in the exit poll results.

Exit polls are dependent on sampling. Hence a margin of error does exist. This describes how close pollsters are in expecting an election result relative to the true population value. Normally, a margin of error plus or minus 3 percentage points is acceptable. However, in the recent times, there have been instances where the poll average was off by a larger percentage. Let us analyze some of the reasons why exit polls can get their predictions wrong.

1

Sampling inaccuracy/quality

Exit polls are dependent on the sample size, i.e. the number of respondents or the number of precincts chosen. Incorrect estimation of this may lead to error margins. The quality of sample data also matters. This includes factors such as whether the selected precincts are representative of the state, whether the polled audience in each precinct represents the whole etc.

2

Model did not consider multiple turnout scenarios

Voter turnout refers to the percentage of voters who cast a vote during an election. Pollsters may often misinterpret the number of people who actually vote based on the total no. of the population eligible to vote. Also, they often base their turnout prediction on past trends. However, voter turnout is dependent on many factors. For example, some voters might not turn up due to reasons such as indifference or a feeling of perception that their vote might not count–which is not true. In such cases, the pollsters adjust the weighting to reflect high or low turnout conditions by keeping the total turnout count in mind. The observations taken during a low turnout is also considered and the weights are adjusted therein. In short, pollsters try their best to maintain the original data.


3

Model did not consider past patterns

Pollsters may commit a mistake by not delving into the past. They can gauge the current turnout rates by taking into the account the presidential turnout votes or the previous midterm elections. Although, one may assume that the turnout percentage over the years have been stable a check on the past voter turnout is a must.

4

Model was not recalibrated for year and time of election such as odd-year midterms

Timing is a very crucial factor in getting the right traction for people to vote. At times, some social issues would be much more hyped and talked-about than the elections. For instance, the news of the Ebola virus breakout in Texas was more prominent than news about the contestants standing in the mid 2014 elections. Another example would be an election day set on a Friday versus on any other weekday.

5

Number of contestants

Everyone has a personal favorite. In cases where there are just two contestants, it is straightforward to arrive at a clear winner. For pollsters, it is easier to predict votes when the whole world’s talking about it, and they know which candidate is most talked about. With the increase in the number of candidates, the task to carry out an accurate survey is challenging for the pollsters. They have to reach out to more respondents to carry out the survey required in an effective manner.

6

Swing voters/undecided respondents

Another possible explanation for discrepancies in poll predictions and the outcome is due to a large proportion of undecided voters in the poll samples. Possible solutions could be

  • Asking relative questions instead of absolute ones
  • Allotment of undecided voters in proportion to party support levels while making estimates

7

Number of down-ballot races

Sometimes a popular party leader helps in attracting votes to another less popular candidate of the same party. This is the down-ballot effect. At times, down-ballot candidates may receive more votes than party leader candidates, even when third-party candidates are included. Also, down-ballot outcomes tend to be influenced by the turnout for the polls at the top of the ballot. So the number of down-ballot races need to be taken into account.

8

The cost incurred to commission a quality poll

A huge capital investment is required in order to commission a quality poll. The cost incurred for a poll depends on the sample size, i.e. the number of people interviewed, the length of the questionnaire–longer the interview, more expensive it becomes, the time within which interviews must be conducted, are some contributing factors. Also, if a polling firm is hired or if cell phones are included to carry out a survey, it will definitely add up to the expense.

9

Over-relying on historical precedence

Historical precedence is an estimate of the type of people who have shown up previously on a similar type of election. This precedent should also be taken into consideration for better estimation of election results. However, care should be taken not to over-rely on it.

10

Effect of statewide ballot measures

Poll estimates are also dependent on state and local governments. Certain issues are pushed by local ballot measures. However, some voters feel that power over specific issues should belong exclusively to state governments. This causes opposition to local ballot measures in some states. These issues should be taken into account while estimation for better result prediction.

11

Oversampling due to various factors such as faulty survey design, respondents’ willingness/unwillingness to participate etc  

Exit polls may also sometimes oversample voters for many reasons. One example of this is related to the people of US with cultural ties to Latin America. Although, more than one-fourth of Latino voters prefer speaking Spanish to English, yet exit polls are almost never offered in Spanish. This might oversample English speaking Latinos.

12

Social desirability bias in respondents

People may not always tell the truth about who they voted for. In other words, when asked by pollsters they are likely to place themselves on the safer side, as exit polls is a sensitive topic. The voters happen to tell pollsters that they have voted for a minority candidate, but they have actually voted against the minority candidate. Social Desirability has no linking to issues with race or gender. It is just that people like to be liked and like to be seen as doing what everyone else is doing or what the “right” thing to do is, i.e., they play safe. Brexit polling, for instance, showed stronger signs of Social desirability bias.

13

The spiral of silence theory

People may not reveal their true thoughts to news reporters as they may believe media has an inherent bias. Voters may not come out to declare their stand publicly in fear of reprisal or the fear of isolation. They choose to remain silent. This may also hinder estimate calculation for pollsters.

The above is just a shortlist of a long list of reasons why exit poll results must be taken with a pinch of salt.

However, even with all its shortcomings, the striking feature of an exit poll is the fact that rather than predicting about a future action, it records an action that has just happened. So you rely on present indicators rather than ambiguous historical data. Exit polls are also cost-effective in obtaining very large samples. If these exit polls are conducted properly, keeping in consideration the points described above, they can predict election results with greater reliability.

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