Another chemical engineer is studying the same process as in Exercise 7 and uses the following experimental matrix.

a. Compute the correlation between temperature and yield, between stirring rate and yield, and between temperature and stirring rate.

b. Do these data provide good evidence that the yield is unaffected by temperature, within the range of the data? Or might the result be due to confounding? Explain.

c. Do these data provide good evidence that increasing the stirring rate causes the yield to increase, within the range of the data? Or might the result be due to confounding? Explain.

d. Which experimental design is better, this one or the one in Exercise 7? Explain.