Relative risk: This risk of a disease symbolized by relative risk is the ration of incidence in exposed persons to incidence in non exposed person.
Incidence of disease among exposed (Ic)
Incidence of disease among non exposed (Io)
RR<1: Exposure is associated with reduced risk of disease.
RR=1: No associated between exposure and disease.
RR>1: Exposure associated with increased risk of disease.
Probability: ƩN (Ʃ=Event that occur, N=Number of event)