Difference between revisions of "Sample Size"
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:[[Method]] - [[Measure]] the [[height]] and foot size of a number of people. | :[[Method]] - [[Measure]] the [[height]] and foot size of a number of people. | ||
: '''Sample Size''' - 5,000,000 people. | : '''Sample Size''' - 5,000,000 people. | ||
| − | This is a [[reliable]] [[investigation]] because there are enough people to [[Mean Average|average]] out any [[anomaly|anomalous]] [[results]]. | + | This is a [[reliable]] [[investigation]] because there are enough people to [[Mean Average|average]] out any [[anomaly|anomalous]] [[results]]. For every short person with large feet there is likely to be a tall person with small feet. |
Revision as of 11:12, 21 March 2019
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.