A article in the IEEE Transactions on Electron Devices

(Vol. ED-33, 1986, p. 1754) describes a study on the effects of two variables—polysilicon doping and anneal conditions

(time and temperature)—on the base current of a bipolar transistor.

Some of the data from this experiment are as follows:

(a) Compute the estimates of the effects and their standard errors for this design.

(b) Construct two-factor interaction plots and comment on the interaction of the factors.

(c) Use the t ratio to determine the significance of each effect with 0.05. Comment on your findings.

(d) Compute an approximate 95% CI for each effect.
Compare your results with those in part

(c) and comment.

(e) Perform an analysis of variance of the appropriate regression model for this design. Include in your analysis hypothesis tests for each coefficient, as well as residual analysis. State your final conclusions about the adequacy of the model. Compare your results to part

(c) and comment.

Anneal (temperature/time) 900/180 1000/15 8.30 10.29 1 x 1020 Polysilicon 8.90 10.30 Doping 7.81 10.19 2 x 1020 7.75 10.10