Sample size calculation is the scientific process used to determine the minimum number of participants, observations, or samples required in a study to produce reliable, statistically meaningful, and scientifically valid results.
In simple terms:
Sample size calculation determines how many participants are needed to answer the research question accurately.
An appropriate sample size is extremely important because:
Proper sample size calculation helps researchers:
Improve the ability to detect true differences or associations.
Prevent missing real effects because of insufficient participant numbers.
Increase scientific credibility and reliability.
Avoid exposing unnecessary participants to interventions or risks.
Prevent unnecessary costs and organizational burden.