The investigators from the previous question have collected some preliminary data from a collaborator. They want to use these data to compare what proportion of people in each treatment group has CD4 count below 200 after one year. The following table shows their observed data: CD4 <200 after 1 year cd4>= 200 after 1 year Total Rifabutin 43 205 248 Rifampin 77 175 252 Total 120 380 500 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 (briefly)