restriction of range
the limitation—via sampling, measurement procedures, or other aspects of experimental design—of the full range of total possible scores that may be obtained to only a narrow portion of that total. For example, in a study of the grade point averages of university students, restriction of range occurs if only students from the dean’s list are included. Range restriction on a particular variable may lead to such negative effects as failing to observe or improperly characterizing a relationship between the variables of interest.