(written as Sample Size)The number of entities (subjects, etc.) in a subset of a population selected for analysis. The size of the sample and the way in which it has been drawn from the population are critical issues in any research study. In some studies, such as trials, particularly where one wants the sample to be representative of the population, size is a major indicator of the statistical power of the analysis. Randomizing the sample selection is necessary for statistical tests to be valid. In other cases, however, as is sometimes the practice in qualitative analysis, non-random samples will be taken to reveal other attributes of the population.
- noun the number of individuals included in a statistical survey