Free Year 10 Maths Analysing Statistical Reports & Bias Worksheet

This worksheet builds statistical literacy, teaching students to reconstruct raw numbers from reported percentages and identify sources of bias and misleading reporting in media statistics. The worksheet is split into warm-up questions, standard questions and then extension questions to test you.

The concepts it covers:

• A percentage change alone (e.g. "up 50%") can be misleading without the original absolute numbers — the same percentage can represent a trivial or a huge real change.
• A percentage point change (the simple difference between two percentages) is different from a relative percentage change (the percentage change expressed as a fraction of the original) — confusing the two is a common source of misleading reporting.
• A truncated (non-zero-start) axis on a graph can make a small real difference look dramatically larger than it is.
• correlation (two variables moving together) does not prove causation (one variable causing the change in the other) — a confounding variable may explain both.
• sampling bias occurs when a sample is not representative of the population it claims to describe (e.g. self-selection, a narrow location, a small or non-random sample); leading questions in a survey can bias the responses themselves.

What your child will practise:

• Reconstructing raw counts from a reported percentage, given the total sample size.
• Distinguishing between a percentage point change and a relative percentage change, and calculate both from the same data.
• Identifying a truncated or otherwise distorted graph, and calculate the true (undistorted) difference it represents.
• Identifying a likely confounding variable behind a reported correlation.
• Identifying the type of bias present in a described survey or sampling method (sampling bias, non-response bias, leading question bias, cherry-picked timeframe).

Every section opens with a worked example, and the download includes a full answer key with step-by-step solutions and teaching notes on the mistakes students most commonly make.