Figure 5. (a) Main effects plots for Y length, measure of the accuracy of the position selection,  relatively to material, cavity, and type of experiment; (b) Main effects plots of the degree of  penetration X in Step 1 (thickness = 1.25 mm for cavity 1 and 1.20 mm for cavity 2); (c) Main effects  plots of the degree of penetration X in Step 2 (thickness = 1.00 mm for cavity 1 and 0.90 mm for cavity  2); (d) Main effects plots of the degree of penetration X in Step 3 (thickness = 0.75 mm for cavity 1 and  0.60 mm for cavity 2). Reproduced with permission from [18].