Sample size refers to the number of subjects in a study. If there is only one sample, then the sample size is designated with the letter “N.” If there are samples of multiple populations, then each sample size is designated with the letter “n.” When there are multiple population samples, then the total sample size of all samples combined is designated by the letter “N.” A study's sample size, or the number of participants or subjects to include in a study, is a crucial aspect of an experimental design. [Source: Encyclopedia of Research Design; Sample Size]
sample size
number needed to treat
epidemiologic research design
methods