Functional analysis of behavior depends upon accurate measurement of both independent and dependent variables. Quantifiable and controllable operations that demonstrate these functional relationships are necessary for a science of human behavior. Failure to implement independent variables with integrity threatens the internal and external validity of experiments. A review of all applied behavior analysis studies with children as subjects that have been published in the journal of Applied Behavior Analysis between 1980 and 1990 found that approximately 16% of these studies measured the accuracy of independent variable implementation. Two thirds of these studies did not operationally define the components of the independent variable. Specific recommendations for improving the accuracy of independent variable implementation and for defining independent variables are
