statistically significant definition sample size
Sample size determination. Sample size determination is the act of choosing the number of observations or replicates to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make inferences about a population from a sample. In practice, the sample size used in a study is determined based on the expense of data collection, and the need to have sufficient statistical power.
While it is important to know this, it is not as useful for comparing effect sizes of multiple studies, as we do in systematic reviews. This is because statistical significance does not take into account sample size (i.e. the number of participants in a study).