Sample Size

**Definition:** The number of units (persons, animals, patients, specified circumstances, etc.) in a population to be studied. The sample size should be big enough to have a high likelihood of detecting a true difference between two groups. (From Wassertheil-Smoller, Biostatistics and Epidemiology, 1990, p95)

**Tree numbers:** - E05.318.370.762 - E05.581.500.902 - N05.715.360.325.692 - N06.850.520.445.762