Open main menu

Sample Size

Key Stage 4

Meaning

Sample size is the number of readings or measurements taken in an investigation.

About Sample Size

The results of an investigation may be unreliable if a small sample size is used.
A small sample size increases the effect of anomalous results on the conclusion of the investigation.
A large sample size allows averages to be taken to reduce the effect of random errors.
A large sample size makes it easier to spot anomalous results.

Examples

Reliable Investigation

Hypothesis - The taller a person, the larger their foot size.
Method - Measure the height and foot size of a number of people.
Sample Size - 5 people.

This is an unreliable investigation because there are not enough people to be certain of any conclusion. They may all have very large feet and be short.

Hypothesis - The taller a person, the larger their foot size.
Method - Measure the height and foot size of a number of people.
Sample Size - 5,000,000 people.

This is a reliable investigation because there are enough people to average out any anomalous results. For every short person with large feet there is likely to be a tall person with small feet.

References

AQA

Sample size, page 10, GCSE Chemistry, CGP, AQA
Sample size, page 10, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Sample size, page 11, GCSE Biology, CGP, AQA
Sample size, page 11, GCSE Combined Science Trilogy; Biology, CGP, AQA
Sample size, page 4, GCSE Biology; The Revision Guide, CGP, AQA
Sample size, page 5, GCSE Combined Science; The Revision Guide, CGP, AQA
Sample sizes, page 10, GCSE Combined Science Trilogy; Physics, CGP, AQA
Sample sizes, page 11, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Sample sizes, pages 262-263, GCSE Biology; Third Edition, Oxford University Press, AQA

Edexcel

Sample size, page 11, GCSE Biology, CGP, Edexcel
Sample size, page 4, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Sample size, page 5, GCSE Biology; The Revision Guide, CGP, Edexcel
Sample sizes, page 11, GCSE Physics, CGP, Edexcel
Sample sizes, page 5, GCSE Chemistry; The Revision Guide, CGP, Edexcel
Sample sizes, pages 10, 11, GCSE Chemistry, CGP, Edexcel

OCR

Sample size, page 5, Gateway GCSE Biology; The Revision Guide, CGP, OCR
Sample sizes, page 5, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR
Sample sizes, page 5, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR