Nested Factors

In nested designs the levels of a factor are nested (the term was first used by Ganguli, 1941) within the levels of another factor. For example, if one were to administer four different tests to four high school classes (i.e., a between-groups factor with 4 levels), and two of those four classes are in high school A, whereas the other two classes are in high school B, then the levels of the first factor (4 different tests) would be nested in the second factor (2 different high schools).
See also, ANOVA/MANOVA .