An article in Industrial and Engineering Chemistry (“More on Planning Experiments to Increase Research Efficiency,” Vol. 62, 1970, pp. 60–65) uses a 25-2 design to investigate the effect on process yield of A = condensation temperature, B = amount of material 1, C = solvent volume, D = condensation time, and E = amount of material 2. The results obtained are as follows:
(a) Write down the complete defining relation and the aliases from the design. Verify that the design generators used were I = ACE and I = BDE.
(b) Estimate the effects and prepare a normal probability plot of the effects. Which effects are active? Verify that the AB and AD interactions are available to use as error.
(c) Interpret the effects and develop an appropriate model for the response.
(d) Plot the residuals from your model against the fitted values. Also construct a normal probability plot of the residuals. Comment on the results.