Opinion Polls, Predictions, and Their Limitations

This lesson examines the role of opinion polls in UK elections — how they work, their influence, and their significant limitations.

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What Are Opinion Polls?

Opinion polls are surveys designed to measure public opinion on political issues, party support, and leader approval. They are conducted by polling companies using samples of the population.

Key UK Polling Companies

Company	Method
YouGov	Online panel surveys; large sample sizes
Ipsos	Telephone and online interviews
Survation	Online and telephone; known for accurate 2017 exit-day poll
Savanta ComRes	Online and telephone surveys
Opinium	Online panels
Deltapoll	Online panels

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How Polls Work

1. Sampling: A representative sample of the population is selected (typically 1,000–2,000 people)
2. Questioning: Respondents are asked about voting intention, leader approval, issue salience, etc.
3. Weighting: Raw results are adjusted to ensure the sample is representative (by age, gender, region, past vote, education, etc.)
4. Reporting: Results are published with a margin of error (typically ±2–3 percentage points)

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Types of Polls