Carryover Effects and Counterbalancing

Abstract

In a counterbalanced design to control for order effects, researcher can use separate groups of subjects, each group receiving treatments in a different order. This is a technique in experimental design that is used to avoid the introduction of confounding variables. In usability testing, this technique is most commonly used when organizing task order. Besides counterbalancing, participants are assigned to orders randomly by using the techniques. Counterbalancing attributes to the systematic variation of the order of conditions in a study, which augments and intensifies the study interval validity. In the context of experimental designs, the most common nuisance factors (confounds) to be counterbalanced are procedural variables that can create order and sequence effects. In quasi-experimental designs, blocking variables (e.g., age, gender) can also be counterbalanced to control their effects on the dependent variable of interest, thus compensating for the lack of random assignment and the potential confounds due to systematic selection bias.