# hw8 - STAT 4220 HW8 (30 points) Due on Thu, April 8 1. (12...

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STAT 4220 HW8 (30 points) Due on Thu, April 8 1. (12 points) Box and Bisgaard (1987) described an experiment to reduce the percentage of cracked springs produced by a particular manufacturing process. Three factors are investigated: temperature of the quenching oil, carbon content of the steel, and temperature of the steel before quenching. A 2 3 design was used; the design and response data, percentage of non- cracked springs, are given in Table 1. Table 1: Planning Matrix and Response Data, Spring Experiment OT ( F) CP ST( F) y 70 0.50 1450 67 70 0.50 1600 79 70 0.70 1450 61 70 0.70 1600 75 120 0.50 1450 59 120 0.50 1600 90 120 0.70 1450 52 120 0.70 1600 87 (a) (2 points) Calculate all the main eﬀects by hand. (b) (2 points) Calculate the OT × ST interaction by hand. (c) (2 points) Calculate the OT × CP × ST interaction by hand. (d) (2 points) Now calculate all the factorial eﬀects by ﬁtting the regres- sion model (use equation (9) of the lecture note). > OT = c(-1,-1,-1,-1,1,1,1,1)

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## This note was uploaded on 06/06/2011 for the course STAT 4220 taught by Professor Smith during the Spring '08 term at University of Georgia Athens.

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hw8 - STAT 4220 HW8 (30 points) Due on Thu, April 8 1. (12...

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