Let us suppose that the event A partitions the sample space S, i.e. AUA = S. The indicator of an event A is the (indicator) random variable IA defined by IA(S) = = [1 if s A ifs & A - 0 The event A occurs if and only if IA = 1. The probability distribution is PIA (0)=P(A) = 1- P(A) PIA (1) = P(A). The corresponding distribution function reads for x < 0 FLA(T) = P(A) for 0