Question: (12 marks). Thirty teeth were randomly allocated into three groups of 10 and a cavity in each tooth filled using one of three preparations. Following immersion in a dye, the percentage of linear leakage occurring at the tooth/restoration interface in each tooth was determined. The results are stored in columns of the file data2_Q1.sav in which the first column contains the percentages of length of penetration (PLP) and the second column contains the preparation used.

a. Produce an analysis of variance (ANOVA) table to determine if there are differences between the preparations using PLP measurement. (2 mark)

b. Produce Q-Q plots or normality test to assess the validity of the ANOVA assumptions. (2 marks)

c. For PLP measurements, conduct Bonferroni post-hoc tests to determine where any differences between the preparations lie. (2 marks)

d. Perform Kruskal-Wallis tests for PLP measurements. What is your conclusion? (2 marks)

e. Use pairwise Wilcoxon rank-sum tests (with Bonferroni correction) to determine where any differences between preparations lie. (2 marks)

f. Which analysis do you think is most appropriate here – ANOVA or a nonparametric approach? (2 marks)