1. Why do national income accountants compare the market value of the total outputs in various years rather than actual physical volumes of production?
2. What problem is posed by any comparison over time of the market values of various total outputs?
3. How is this problem resolved?

Suppose that, on the basis of a nation’s production possibilities curve, an economy must sacrifice 10,000 pizzas domestically to get the 1 additional industrial robot it desires but that it can get the robot from another country in exchange for 9,000 pizzas. now consider the following statement: “through international specialization and trade, a nation can reduce its opportunity cost of obtaining goods and thus ‘move outside its production possibilities curve.’”