Economists recommend overcoming this adding up problem by measuring opportunity costs in terms of the values of what is sacrificed. We will encounter this adding up problem and economists solution to it in the following section of this tutorial. We suggested earlier that it is possible to construct an opportunity set for the economy as a whole. Consumer goods consist of such things as food, movies, bus fare, haircuts, etc. Consumer goods are used up in the course of daily living.
Capital goods consist of buildings, blast furnaces, tractors, computers, etc.
To be more complete in our definition of capital goods we might also include the production of capital that is embodied in humans through formal education and other kinds of training. We might also include the capital that is supplied to us by nature in the form of fossil fuels, minerals, soil, forests, etc. Just as in the movies and beer example we could graph the different mixes of consumer and capital goods that could be produced using all of the labour and existing capital currently available in the economy. Since we are aggregating over many kinds of consumer and capital goods the units on each axis will either be a quantity index or a real value measure. These measures are discussed in some detail in another tutorial on index numbers and real value measures but in order to understand the basic idea of opportunity cost for the economy as a whole we need not be concerned about measurement issues here.