Sample size

Sample size is a term used in statistics and research design to refer to the number of observations or replicates (the repetition of an experimental condition) used in an experiment. The size of a sample influences the accuracy of the study's results, and larger sample sizes reduce the chance of sampling error because they allow for a more accurate representation of the population.

Definition

In statistics, a sample is a set of data collected and/or selected from a statistical population by a defined procedure. The elements of a sample are known as sample points, sampling units or observations. The size of the sample is denoted by the letter n.

Importance of Sample Size

The size of a sample, also known as the number of units (observations) in the sample, is a crucial factor in determining the accuracy and reliability of the study's results. Larger sample sizes provide more accurate mean values, identify outliers that could skew the data, and provide a more complete picture of the data distribution.

In experimental research, sample size is crucial because it can influence the statistical power of the study. Statistical power is the probability that a test will correctly reject a false null hypothesis. Larger sample sizes increase the statistical power of the study, making it more likely that the researchers will be able to detect a true effect if one exists.

Determining Sample Size

Determining the appropriate sample size in a study is a balance between practicality and statistical power. The sample size should be large enough to have a high likelihood of detecting a true effect, but not so large that it wastes resources or exposes unnecessary numbers of subjects to any potential risk.

Several factors can influence the determination of sample size. These include the level of precision required, the level of confidence desired, the expected variability in the population, and the size of the effect that the researcher is trying to detect.

See Also

• Statistical population
• Sampling (statistics)
• Statistical power
• Research design

References

Sample size Resources
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