=+18. To see whether the force in drilling is affected by the drilling speed (A), feed rate (B), or material used (C), an experiment using four speeds, three rates, and two materials was performed, with two replicate samples drilled at each combination of levels of the three factors. A software package was used to obtain the sums of squares for the experimental data: SSA 5 19,149.73, SSB 5 2,589,047.62, SSC 5 157,437.52, SS(AB) 5 53,238.21, SS(AC) 5 9,033.73, SS(BC) 5 91,880.04, SSE 5 56,819.50, and SST 5 2,983,164.81.