Fiducia TogetherSampling
Studying part of a population to say something about all of it.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
A sample is a subset of a population. Random sampling gives everyone an equal chance; stratified sampling takes proportional numbers from each subgroup.
Where it applies
Both tiers, and in geography and science practicals.
How it works
A sample is only useful if it represents the population. Bias creeps in through how people are chosen, who declines, and where and when you ask.
Larger samples reduce random error; they do not fix bias.
How to use it in your work
When asked to criticise a sampling method, name the specific bias and who is excluded. "Asking shoppers on a Tuesday morning misses anyone at work."
For stratified sampling, show the calculation for each stratum — the marks are in the working.
Where to get help
Your teacher, your board's specification for what is on your paper, and Bitesize for worked examples. The maths song runs the topics in order.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Maths Song The GCSE maths topics, in order.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.