Orthogonal Experimental Design

The L9(3^4) orthogonal design reduces the number of required EA treatment combinations from 81 to 9, while preserving balanced estimation of main effects. Each level of each factor is represented by 33 participants across the nine EA groups because each factor level appears in three groups of 11. Factors with p ≤ 0.05 in ANOVA are considered statistically significant; for significant factors with three or more levels, post hoc pairwise comparisons use Bonferroni correction. Range analysis using K values and R values determines the relative importance of each factor, with larger R values indicating greater factor influence. The orthogonal design evaluates main effects only and is not powered or structured to assess interaction effects between treatment factors.