Graeco-Latin is simply two superimposed Latin Square design with one using the Latin Letters and the other using the Greek letters, resulting in a design with four factors (Figure 9). Therefore, the error can be controlled in three directions by blocking three nuisance factors. Two treatment factors could also be tested by blocking only two nuisance factors.

Figure 9. Graeco-Latin Square Design of Experiments

Graeco-Latin Square Design of Experiments Analysis Model

The analysis model for the Graeco-Latin Square Design is provided in Equation 3.