ABSTRACT
The empirical demonstration that changes in behavior are functionally related to manipulated changes in the environment is a fundamental principle of behavior analytic research (Baer, Wolf, & Risley, 1968). In other words, researchers must demonstrate that changes in a dependent variable are functionally related to systematic, controlled, and measurable changes in an independent variable. This demonstration requires the representation of the independent variable by known physical parameters of an environmental event. Without clear and unambiguous specification of the independent variable, there can be no definitive conclusions regarding a functional analysis of behavior (Johnston & Pennypacker, 1980; Sidman, 1960).
