Sexually active life expectancy is the average number of years remaining for a person to be sexually active. This population-based indicator extends the concept of health expectancy to the measure of sexuality (via sexual activity). Calculation of sexually active life expectancy uses the age-specific prevalence data on sexual activity in conjunction with life table data on survival probabilities to partition the number of person-years into years with and without sexual activity, which is based on the Sullivan method. The measure of sexually active life expectancy was introduced by Lindau and Gavrilova.