Refer to Exercise 9.25. The same type of data on mg/mL and pH were generated at 40°C as we...

Refer to Exercise 9.25. The same type of data on mg/mL and pH were generated at 40°C as were obtained at 30°C in Exercise 9.25. The data are shown here.

a. The computer output is shown here for the analysis of variance of part (a) for both response variables y1 = mg/mL and y2 = pH. What is the effect of the three factors on the mean active ingredient of the drug? Use α = .05.

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b. Using the computer output for the analysis of variance of part (a) for both response variables y1 = mg/mL and y2 = pH, what is the effect of the three factors on the mean pH of the drug? Use α = .05 and profile plots in reaching your conclusions.

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c. Are your conclusions about the effects of storage time and temperature on mean pH the same for both laboratories?

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d. Are your conclusions about the effects of storage time and temperature on mean active ingredient of the drug the same for both laboratories?

Exercise 9.25

Researchers were interested in the stability of a drug product stored for four storage times (1, 3, 6, and 9 months). The drug was manufactured with 30 mg/mL of active ingredient of a drug product, and the amount of active ingredient of the drug at the end of the storage period was to be determined. The drug was stored at a constant temperature of 30°C. Two laboratories were used in the study with three 2-mL vials of the drug randomly assigned to each of the four storage times. At the end of the storage time, the amount of the active ingredient was determined for each of the vials. A measure of the pH of the drug was also recorded for each vial. The data are given here.

a. Write a model relating the response measured on each vial to the factors length of storage time and laboratory.

b. Display an analysis of variance table for the model of part (a) without computing the necessary sum of squares.