The problem of generality in experimentation

Abstract

Psychologists are concerned with questions such as: To what extent can the therapy applied to subject X be valid for subjects Y and Z, provided they share similar characteristics with the first? To what extent is the study conducted with the 7th-grade class at School A applicable to Schools B, C, and D? How many subjects are needed for the experiment to yield representative data on the experimental situation?

This paper reflects on these questions by analyzing the issue of generality from two perspectives: first, as an additional phase in any scientific study; and second, by clarifying that the problem of generality is inherent in both the internal and external validity of all experimental research.