N

the number of scores in a sample.

For instance, in a study of driving ability in men and women, if 15 people participate in the study, then N=15.

In many studies, participants (or "subjects") are often divided into groups or conditions. For instance, in the above example of a study of driving ability, there were 10 males and 5 females. These numbers are referred to with a lowercase "n", while the total number of subjects, 15, is uppercase N. In this example, we might call the number of males "n₁" and the number of females n₂.

Therefore, N=15, but this is divided into males (n₁=10) and females (n₂=5). As this example shows, N (capital N) is used for the total number of scores collected, combining all groups.

Small n

n (small n, or lower case n) is used to denote the number of scores in a single group in