The performance measure is the long-run average cycle time (hours) weighted by percentage of different products. The quantity c ☆ is the price to buy one fast oxidizing machine, which equals $3.25 millions (Table 5 in the Wafer Manufacturing System) ; Δ0 is the minimum acceptable decrease in long-run cycle time that would justify a capital expenditure of $3.25 millions, and Δ1 is the decrease in long-run cycle time that we do not want to miss if it can be achieved for $3.25 million. The screening results are given in Table 7 with different combinations of Δ0 and Δ1.
To summarize, the bigger Δ0 and Δ1 are, the fewer factors are identified as important, and the fewer replications are required. The factors identified as important are consistent in these four cases. When Δ0 increases to 5 and Δ1 increases to 8, the single most important factor is determined, which is the number of AGVs in the system.