Unit 5 Flashcards
Experimental Design
Repeated, systematic presentation and removal of an independent variable (IV) while measuring changes in the dependent variable (DV), and holding other factors constant
The primary goals of experimental design
To demonstrate a functional relation between the IV and DV To evaluate the interventions once they are decided upon
Functional relation
Exists when changes in an antecedent or consequent stimulus class consistently alter a dimension of a response class
Internal validity
The extent to which an analysis assures that measured changes in behavior are due to the manipulation and NOT due to uncontrolled extraneous variables
External Validity
The extent to which a study’s results are generalizable to other subjects, settings, or behaviors
History, maturation, testing, instrumentation, diffusion of treatment, regression towards the mean, selection bias, attrition
Threats to internal validity
Introduction of the IV may coincide with other events in the person’s life (and those other events could have produced the effects)
History
Natural developmental events or learning experiences may coincide with the introduction of the independent variable to produce the change
Maturation
Changes in the dependent variable may have come about as a function of repeated exposure to the experimental arrangements
Testing
Changes may reflect modifications in the measurement systems rather than effects of the IV
Instrumentation
Inadvertent, uncontrolled “seepage” of the treatment to control conditions or control subjects
Diffusion of treatment
Changes occurred because baseline measurements were NOT representative of the natural state of events; perhaps less relevant to single-case designs because of repeated measures
Regression towards the mean
The assignment of subjects to groups may have biased the outcome even in the absence of any intervention; Perhaps less relevant to single-case designs because participants serve as their own controls
Selection bias
