The percentage of the population in any given age group who are economically active, either as employees, self-employed, or unemployed, on the assumption that the unemployed would all work if jobs were available. Participation rates can be calculated for different categories of workers. Participation rates tend to vary with age, being lower among the young, many of whom are still in full-time education, and among the old, who are frequently retired; they are highest among those aged 20–50.