'Pairwise Balanced' Latin Square Should Always be Used for within-Subjects Designs.

The use of repeated measures designs in many areas of psychological research has prompted concern for the potential confounds inherent in the interpretation of treatments that have been included as within-subject variables. Of the solutions proposed for this problem, the most commonly adopted strategy is the use of Latin Square counterbalancing orders for treatment presentation. Traditional Latin Square designs ensure that each of the experimental treatments included as part of the within-subject factors is administered in each serial position of the treatment sequence. The present paper presents a discussion of a novel technique for the generation of a subset of Latin Squares that control for two additional features that are seen to be important in many research situations, i.e., pairwise priority and distance. Such Latin Squares are referred to as pairwise balanced Latin Squares. The relative advantages of using such Latin Squares in repeated measures designs are discussed. Author