2. You are the quality trainee for a heavy equipment company, and you are working in a project to improve the overall order lead time. By applying the Six Sigma methodology, your team has identified two vital factors that affect the lead time performance: type of order system and packing material. Your company thus forms a team including you to collect 12 sets of data as follows (set = 0.05): Observations Order System Pack Hours 1 X A 10.17 2 X A 11.34 3 X A 11.01 4 Y A 12.52 5 Y A 12.57 6 Y A 14.06 ? X B 13.81 8 X B 13.78 9 X B 13.89 10 Y B 9.41 11 Y B 7.97 12 Y B 7.94 Factorial Regression: Hours versus Order System, Package Materials Model Summary R-sa R-sq(adi) R-sq(pred) 93.49% 91.05% 85.36% Coded Coefficients Term Coef SE Coef T-Value P-Value Constant 11.539 0.196 58.96 0.000 Order System 0.794 0.196 4.06 0.004 Packing Materials 0.406 0.196 2.07 0.072 Order System x Packing Materials 1.899 0.196 9.70 0.000 Man Lace Flat For Hour Interaction Plot for Hour FlmedWaan Pasing Mark Order Systern Packing Mate 12 14 " 2 Mean of Hour 121 Order System Questions a) Which factor(s) [ordering system and/or packing materials] is significantly influencing the overall order lead time? (4 marks) b) Does the interaction between order system and packing materials significantly affect the overall order lead time and why? (4 marks) c) According to the main effect plot and the interaction plot as shown below, if you select ordering system X, which packing materials do you prefer? (4 marks) d) What is the best combination of the factor levels that minimizes the overall order lead time? (4 marks)