An article in the Journal of Coatings Technology (Vol. 60,

Chapter 14, Problem 14-66

(choose chapter or problem)

An article in the Journal of Coatings Technology (Vol. 60, 1988, pp. 2732) describes a 24 factorial design used for studying a silver automobile basecoat. The response variable is distinctness of image (DOI). The variables used in the experiment are A Percentage of polyester by weight of polyester/melamine (low value 50%, high value 70%) B Percentage of cellulose acetate butyrate carboxylate (low value 15%, high value 30%) C Percentage of aluminum stearate (low value 1%, high value 3%) D Percentage of acid catalyst (low value 0.25%, high value 0.50%) The responses are (1) 63.8, a 77.6, b 68.8, ab 76.5, c 72.5, ac 77.2, bc 77.7, abc 84.5, d 60.6, ad 64.9, bd 72.7, abd 73.3, cd 68.0, acd 76.3, bcd 76.0, and abcd 75.9. (a) Estimate the factor effects. (b) From a normal probability plot of the effects, identify a tentative model for the data from this experiment. (c) Using the apparently negligible factors as an estimate of error, test for significance of the factors identified in part (b). Use 0.05. (d) What model would you use to describe the process, based on this experiment? Interpret the model. (e) Analyze the residuals from the model in part (d) and comment on your findings.