Relative risk of a disease measures which of the following-

Relative risk = Incidence among exposed /incidence among non exposed A typical case control study does not provide incidence rate from which relative risk can be calculated directly because there is no appropriate denominator or population at risk to calculate these rates.in general relative risk can be exactly determined from a coho study Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 86