‘Suppression Polls’, or an Example of Social Desirability Bias?
By: Nicola Thomas
Tags: Pollsters, Psychology, Voter Suppression, Trump, Election 2020

Are bad polls fake? What are the point of polls? Well, political polling is designed to take the pulse of an electorate , yet it isn’t a dynamic measurement. It is fixed at a certain time — e.g. when the respondent answers the poll.

This is at odds with how our opinions change over time. Elections are dynamic, voter’s opinions change over time in response to campaigns, information related to campaigns, and the happenings of the world around them (e.g. a pandemic, a recession, need for health care).

So, embedded in the nature of polling is a static measurement, trying to capture a dynamic opinion, this alone will create a margin of error in polling. That is not even considering the importance of representative samples, e.g. are the people who take the polls representative of the people who vote? How are they recruited, online & through land lines? What about voters who don’t have internet or a land line etc. Or more timely — how do you get a representative sample of people who believe in conspiracies — e.g. QANON. Those demographics are unlikely to participate in traditional polling due to a high level of distrust in traditional systems. How can those demographics be polled in the future?

Yet ignoring the potential sampling problems, and the static measurements that can hinder the accuracy of polls, do negative polls act as a suppression tactic?

Well, it is known that polling results influence the candidates. Candidates generally adjust their campaign strategies if they are shown to be behind, or carry on as they were if they are doing well. But do the polls influence voter behaviour?

Trump assumes that the polls showing him as trailing mean that his voters won’t engage with the election because they feel it wouldn’t make a difference. Yet, research has found a weak affect of polling on influencing voter turnout.

Researchers define suppression polls as polls “which slander a candidate with the specific objective of discouraging turnout”. Yet, considering the turnout for this election is projected to be 66.4%, the highest since 1900, and considering how much of the popular vote is for Trump, it seems the polls haven’t discouraged turnout, but conversely, encouraged it.

Another worry of ‘suppression polling’ is that by inflating a candidates lead there are ‘bandwagon voters’. That is, voters who jump on the winners bandwagon. But again, research shows voters don’t turnout to ‘bandwagon’, but rather they most frequently turnout to effect the outcome of the election. In this case, it seems the polling which showed Biden in the lead may have emboldened Trump supporters to vote — it may have mobilised his base to turnout to shape election outcome.

Beyond the issues with polling in general, and the fact that definition of suppression polls in research does not support the notion that these polls were suppressing, I present an alternative for why the polls in both 2016 and 2020 underestimated Trump.

I was talking to a Trump supporter earlier this year, and I asked what he did and didn’t like about Trump. He said that he liked his economic plans and how savvy he is in bringing manufacturing back to the USA. He didn’t like how uncouth Trump is when he speaks, and how unpolished and offensive he is.

These reasons make sense and hint at a larger problem with polling an unpolished, offensive candidate: the social desirability bias.

Social desirability bias is a bias which affects how people answer surveys. As a social scientist, I am all too aware that people will answer questions to conceal preferences which aren’t perceived to be socially desirable. Research has found socially desirable responding makes people conceal political preferences when they are socially inappropriate.

A study which used real polling data from the US 2016 election showed that due to social desirability bias, polling overstated agreement with Clinton relative to Trump.

Ultimately, socially desirable responding often biases unincentivized surveys. But, media, campaigns, and markets all employ unincentivized polls to make predictions about electoral outcomes. I believe this bias is uniquely important in any election with Trump as a candidate, giving how extremely polarising he is.

Understanding methodological bias is so important, mostly to help people realise there are well understood, well researched explanations for why polling can be wrong. Explanations that go beyond Trump vs the world. Explanations that hopefully reduce polarisation and don’t lead to an increase in violence when frustrated voters feel like the media has intentionally misreported results to change the election.