An experiment is run in a semiconductor factory to investigate the effect of six factors on transistor gain. The design selected is the 26−2 IV shown in Table P8.15.

(a) Use a normal plot of the effects to identify the significant factors.

(b) Conduct appropriate statistical tests for the model identified in part (a).

(c) Analyze the residuals and comment on your findings.

(d) Can you find a set of operating conditions that produce gain of 1500 ± 25?