note that a dollar today is worth more to an individual than a dollar in the future,so those future income gains must be discounted accordingly,as is done in equation 8.1 the rate of return will be higher whenever the discount rate is lower, the indirect costs are lower,or the benefits are higher.this analysis was performed from the individual's point of view in the three right hand columns of ตาราง8.1 .notice that in sub-saharan africa and asia,the private rate of return to primary education is about 40%despite this extraordinary return,many families do not make this investment because they have no ability to borrow even the meager amount of money that a working