this is taken to be 66 years.two earnings profiles are presented-for workers with primary school but no secondary education and for those with a full secondary (but no higher)education.primary graduates are assumed to begin worker age 13,secondary graduates at age 17.for an individual in a developing country deciding whether to go on from primary to secondary education,4 years of income are forgone.this is indirect cost,as labeled in the diagram.the child may work part time,a possibility ignored here for simplicity,but if so,only part of the indirect-cost area applies.there is also a direct cost,such as fees, school uniforms,books,and other expenditures that would not have been made if the individual had left school at the end of the primary grades.over the rest of the person's life,he or she makes more money each year than would have been earned with only a primary education.this differential is labeled'benefits'in the diagram.before comparing cost with benefits