<prompt> Ratio of incidence among exposed and non exposed is known as -Risk ratioOdds ratioAttributable riskSAR  <response>: Ans. is a i.e., Risk ratio Relative risk risk ratioo Relative risk is the ratio of the incidence of the disease or death among exposed and the incidence among nonexposed.RR Incidence of disease among exposedIncidence of disease among nonexposedo RR is a direct measure of the strength of the association between the suspected cause and effect.o A relative risk of one indicates no association.o A relative risk greater than one indicates positive association between the exposure and the disease under study,o For example, a RR of 2 indicates that the incidence rate of disease is 2 times higher in exposed group as compared with unexposed -100 increase in risk.o A relative risk of less than one indicates negative association, i.e. exposure to a factor will decrease the incidence of disease e.g. exposure to vit A decreases the incidence of skin cancer. 