An article in Advanced Semiconductor Manufacturing Conference (ASMC) (May 2004, pp. 325€“29) stated that dispatching rules and rework strategies are two major operational elements that impact productivity in a semiconductor fabrication plant (fab). A four-factor experiment was conducted to determine the effect of dispatching rule time (5 or 10 min), rework delay (0 or 15 min), fab temperature (60 or 80°F), and rework levels (level 0 or level 1) on key fab performance measures. The performance measure that was analyzed was the average cycle time. The experiment was blocked for the fab temperature. Data modified from the original study are in the following table.

(a) What effects are confounded with blocks? Do you find any concerns with confounding in this design? If so, comment on it.

(b) Analyze the data and draw conclusions.

Average Cycle Rework Temperature TimeRun (min) Dispatching Rework Rule Time Delay (min) (min) Fab ("F) Run Level 60 218 10 80 256.5 80 231 10 302.5 15 80 298.5 10 15 60 314 15 60 249 10 15 80 241 2. 4) 6.