Statistics and data · Solid · Dissertation

Why do opinion polls miss?: a maths EPQ idea

Why it works as an EPQ

Sampling, margins of error and weighting are A Level ideas with real consequences, and well-documented misses to analyse.

Scope and difficulty

Solid. Solid. Pick one or two elections and a few explanations.

The maths

Builds on these A Level topics: Sampling and data · Statistical distributions · Hypothesis testing.

You would learn:

• Margins of error for proportions
• Weighting and quota samples
• Non-response bias

Learning maths beyond the course is expected in a maths EPQ, but you must understand and explain everything you use.

One possible plan

1. Derive the margin of error for a simple random sample.
2. Compare final polls with results for one or two elections.
3. Weigh the explanations given in published inquiries.
4. Judge how much uncertainty polls should report.

Pitfalls

• Treating a quota sample as random.
• Political opinion in place of analysis.

Where to start reading

• British Polling Council
• Search for: inquiry into the 2015 British general election opinion polls

Prefer books, lecture notes, journal articles and official data to a single website, and record every source as you read (how to reference).

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Your EPQ must be your own work. These pages coach: ideas, structure, checklists and planning. Submitting text, proofs, code or analysis written by someone else or by an AI tool as your own is malpractice. How to use help and AI honestly.