Sampling Frames
Master Sampling Frames for GCSE Statistics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA and Edexcel. A sampling frame is a list of all members of the population from which a sample is drawn.
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Topic overview
A sampling frame is a list of all the members of the population from which a sample is taken.
Examples include a school register, an electoral roll, or a membership list. Each member is usually numbered so that a sampling method can be applied to the list.
The sampling frame must be complete and up to date, or bias is introduced. If a school register omits students who joined recently, those students can never be selected, so the sample cannot properly represent the school. Sometimes no complete sampling frame exists — there is no list of everyone who visits a park — and then other sampling methods must be used.
Revision notes
What a sampling frame is
A list of all the members of the population from which the sample will be taken.
Examples: a school register, an electoral roll, a club membership list. Members are usually numbered so a sampling method can be applied.
Why it must be complete
Anyone missing from the frame can never be selected, so they are excluded from the investigation entirely.
This introduces bias, because the sample cannot represent the parts of the population that were left out. The frame must also be up to date.
When no frame exists
For some populations no complete list is available — visitors to a park, or shoppers in a town centre.
Random and systematic sampling cannot be used without a frame, so methods such as quota, cluster or opportunity sampling are used instead.
Key points
- A sampling frame lists all population members.
- Members are usually numbered.
- Examples include registers and electoral rolls.
- The frame must be complete and up to date.
- An incomplete frame introduces bias.
- Some populations have no available frame.
Worked examples
Example 1
State what is meant by a sampling frame. [1 mark]
Working
Example 2
Explain why an out-of-date sampling frame may introduce bias. [2 marks]
Working
Example 3
Give one example of a population for which no complete sampling frame exists. [1 mark]
Working
Common mistakes
Confusing the sampling frame with the sample.
The frame is the list of everyone; the sample is who is selected from it.
Assuming a frame always exists.
Many populations have no complete list available.
Forgetting that the frame must be current.
An out-of-date list excludes recent additions and introduces bias.
Saying the frame is the population.
It is the list of the population, which may be incomplete.
Exam tips
- Define the frame as a list of the whole population.
- Link an incomplete frame directly to bias.
- Give a concrete example such as a school register.
- Note which sampling methods need a frame.
Key terms
- Sampling frame
- A list of all members of the population.
- Electoral roll
- A list of registered voters, used as a sampling frame.
- Bias
- A systematic tendency for a sample to misrepresent the population.
- Complete
- Including every member of the population.
Related topics
Written and reviewed against the current AQA and Edexcel specifications. Spotted an error? Let us know.