Clinical Research Glossary

sample size sample size


The number of participants in a study or study group.

Example of sample size in a sentence

A study’s sample size should ensure there will be enough participants enrolled to answer the study question.

More Info

The sample size must be able to be reached so that the study question can be answered. A statistician helps to calculate the sample size to ensure it is large enough to answer the study question. Sample size is often reported as n = . For example, a study with 100 participants would have its sample size described at n=100.

Other info to think about when joining a study

The study team may tell you about the sample size of the study. You may also read about the sample size of the study in the consent form.

You may want to ask how many people have already enrolled in the study before you agree to join.

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