Sample Size
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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.