Cohen is power. Inferential statistics primarily invoke the following four key concepts: sample size, significance criterion, effect size, and statistical power. Cohen elegantly developed the maths, benchmarks, and key semantics associated with statistical power.
Statistical power is the long-term probability of rejecting the null hypothesis (typically assumed to be no difference between treatments) as defined by Cohen 1992. In a brief exploration of power for pilot experiments with limited numbers of available subjects, here are several current resources to facilitate the exploration of appropriate sample sizes.