A researcher is testing the effects of metal contamination on the number of species found in marine invertebrates (sponges, bryozoans and sea squirts etc.). In particular, they would like to know whether copper enrichment reduces species richness, but the richness also depends on whether the substrate is vertical or horizontal. Consequently, they ran an experiment where species richness was recorded in samples from the six combinations of Copper (\"None", \"Low", \"High") and Orientation (\"Vertical\Normal P-P Plot of Residual for Richness 1.0 . 00 0.8 O O O 0.6 O Expected Cum Prob 0.4 0.2 0.0 0.0 0.2 0.4 0.6 0.8 1.0 Observed Cum Proba) What are the sources of variation in Flichness that are illustrated in the side-by-side boxplots and analyzed in an ANOVA procedure? [3 marks] b) What are the appropriate statistical terms for the variables Richness and Copper? [2 marks] c) What is the most appropriate statistical method to apply to this data? Fully justify your selection. [4 marks] d) Write appropriate null hypotheses (Hg) for this question (don't worry about the alternative hypotheses this time). Be sure to label your hypotheses clearly, so we can tell what goes with what. [5 marks] e) Referring to any available and relevant information, write one sentence explaining to what extent the following assumptions and conditions are met, or if there is insufficient evidence to tell: 0 Equal variance assumption [3 marks] . Independence assumption [3 marks] . Normal Population Assumption [3 marks] f) Making reference to the SPSS table, interpret the output of the test at the 5% significance level. [5 marks] g) Which rows in the SPSS table can be ignored for the purposes of this class? [4 marks] h) Describe how the interaction plot below justifies the inclusion of an interaction term in the ANOVA model. [4 marks] Estimated Marginal Means of Richness Orientation 70 Horizontal vertical 65 60 Estimated Marginal Means 55 50 45 High Low None Copper