“…After all, understanding time allocation is just as understanding life itself. After Becker's (1965) pioneering work, time value was looked at in a single dimension, namely as the opportunity cost of work time equal to the wage rate, a property that followed the absence of work time in utility, criticized soon after by Johnson (1966), Oort (1969) and Evans (1972). By 1971, De Serpa identified three concepts of time value: the value of time as a resource, the value of assigning time to an activity, and the value of saving time in a constrained activity.…”