Question 3 [20 marks].

An experiment was designed to study the influence of four lev- els of operating temperature (100oC, 120oC, 140oC and 160oC) and four types of face-plate glass (1,2,3 and 4) in the light output of an oscilloscope tube. Each of the 16 treatment combinations of glass type and operating temperature was randomly trailed in the exper- iment for three times (i.e three oscilloscope tubes). The light output of each oscilloscope tube (named lightoutput) was measured.

a) What experiment design has been used here? [1 marks]

b) Write out the effects model for the design suggested above; [1 marks]

c) State the assumptions of the model; [2 marks]

d) Briefly explain how to check each of the model assumptions. [2 marks]

e) The lightoutput were analysed with respect to both factors studies. Some of nu- merical summary of the data from this experiment and partially completed ANOVA table from Minitab are presented below. Complete the ANOVA table, using your knowledge and the information given below.