2. In an experiment aimed at assessing the effects of prolonged inhalation of cadmium oxide, 35 laboratory rats were randomly allocated to an experimental group and a control group. The 20 rats in the experimental group were continuously exposed cadmium oxide for 6 weeks and no intervention was given to the 15 rats in the control group. The variable of interest was the hemoglobin level (g/dL) following the experiment. The results are given in Table 12.9.

Please answer the following questions:

(a) What is the design of this study? Is it appropriate to conduct a two independent samples t-test test here? If not, choose an appropriate method, and explain what is the advantage over the two independent samples t-test in this case?

(b) What is the underlying idea of this method? How do you rank the subjects in the process of testing?

(c) State H0 and H1, test the hypothesis using the appropriate method and interpret the results.