Relative Risk for TB by TST induration 10 Relative Risk 1 13+ 0-2 3-4 5-7 8-12 Induration Cross-sectional study Prospective study (14 years) Q5. When are associations observed from cross-sectional (prevalence) studies similar to those observed from prospective studies? (Hint: When are the OR and the RR the same? When are prevalence and incidence the same?) Relative Risk for TB by TST induration 10 Relative Risk 1 13+ 0-2 3-4 5-7 8-12 Induration Cross-sectional study Prospective study (14 years) Q5. When are associations observed from cross-sectional (prevalence) studies similar to those observed from prospective studies? (Hint: When are the OR and the RR the same? When are prevalence and incidence the same?)