e. What is the problem with comparing all pairs of ARVs using a ttest at alpha=0.05 for each? 2. (15 pts) in the study described in problem 1, the investigators summarized the data in the following 2x2 table based on whether the CD4 count dropped below 200 by the end of the study. The following table shows their observed data: CD4 = 200 at end of Total 50 260 500 a. What is the ARV1-to-ARV2 odds ratio for this data? What is the ARV1-to- ARV2 relative risk (also known as the Risk Ratio)? b. If you don't know how the sampling was designed (based on ARV, based on CD4 count, or based on taking a group without regard to ARV or CD4 count), is it better to use the odds ratio or the relative risk? Why (briey)? c. What is the null hypothesis, expressed in terms of whichever measure you chose in part b? d. Fill in the following table with the expected counts, under the null hypothesis that there is no association between ARV regimen and probability of CD4