1. For the clinical trial considered in Tutorial 5, Question 3, treat the operation as a single factor and the four combinations of operation A and B as the levels, i.e., treat (no,no), (yes, no), (no, yes) and (yes, yes) respectively as level 1, 2, 3 and 4. The data is re- described as follows: Level Measurements 31.02 24.03 28.37 26.57 25.83 25.87 26.08 24.89 28.32 29.98 20.41 20.31 23.45 13 35.71 34.83 35.13 38.30 33.12 42.07 38.69 43.16 33.11 42.47 40.45 31.95 38.69 42.26 14 25.85 39.77 32.88 46.29 33.07 29.23 31.39 28.28 22.43 38.42 10 49.47 42.29 48.60 47.10 33.63 32.00 49.31 50.81 8 (i) [5 marks] Write R-codes to fit the following model: y = Bo + Buz + Bus + BAus + E, where uj's are the dummy variable defined in the conventional way for the factor operation. Provide the summary table and the estimated variance matrix of the estimated regression parameters. (ii) [10 marks] Do a general exploring to find out whether there are any significant contrasts among the four treatment means. Identify at least FOUR apparently significant contrasts. Give reasons why you identify them. Test their significance by controlling the family-wise type I error rate at level o = 0.05. (iii) [5 marks] Construct 95% simultaneous confidence intervals for the contrasts iden- tified in (ii)