Question: A recent study examined the pulmonary function of 135 asbestos product workers. Examined was forced vital capacity (FVC) and percent predicted forced vital capacity (PFVC). The reason for the latter had to do with accounting for the effects of age, height, sex and race. Of these, age is particularly important because FVC is known to change with age. The investigators, in developing their analysis plan, learned from their literature review that the development of clinical manifestations of asbestos exposure requires a minimum of 20 years. Therefore, the data were partitioned into two groups: (1) Length of exposure less than 20 years (n=66) and (2) Length of exposure 20 or more years (n=69). The following sample statistics were obtained

b. (2 points) In your opinion, should a one sided test or a two sided test be performed? Explain your answer in 1-2 sentences at most.

c. (3 points) Perform the appropriate test to determine if it is appropriate to assume equality of variances Use a 0.05 significance level threshold for declaring statistical significance.

d. (3 points) Using your answers to questions #9a-#9c, perform the appropriate test of equality of mean pulmonary function in the two groups. Note – I am asking for just ONE hypothesis test. Do not test equality of mean for both FVC and PFVC. Pick just one.