国民收入源自何方去向何处PPT.ppt

After showing definition of private saving, - give the interpretation of the equation: private saving is disposable income minus consumption spending - explain why private saving is part of the supply of loanable funds: Suppose a person earns $50,000/year, pays $10,000 in taxes, and spends $35,000 on goods and services. There’s $5000 remaining. What happens to that $5000? The person might use it to buy stocks or bonds, or she might put it in her savings account or money market deposit account. In all of these cases, this $5000 becomes part of the supply of loanable funds in the financial system. After displaying public saving, explain the equation’s interpretation: public saving is tax revenue minus government spending. Notice the analogy to private saving – both concepts represent income less spending: for the private household, income is (Y-T) and spending is C. For the government, income is T and spending is G. The Delta notation will be used throughout the text, so it would be very helpful if your students started getting accustomed to it now. If your students have taken a semester of calculus, tell them that ?X is (practically) the same thing as dX (if ?X is small). Furthermore, some basic rules from calculus apply here with ?s: The derivative of a sum is the sum of the derivatives: ?(X+Y) = ?X + ?Y The product rule: ?XY = (?X)(Y) + (X)(?Y) In fact, you can derive the two arithmetic tricks for working with percentage changes presented in chapter 2. Just take the preceding expression for the product rule and divide through by XY to get (?XY)/XY = ?X/X + ?Y/Y, the first of the two arithmetic tricks. First, in the box at the top of the slide, we plug the given value for the MPC into the expression for ?S and simplify. Then, finding the answers is straightforward: just plug in the given values into the expression for ?S. Notes: 1. The huge deficit in the early 1940s was due to WW2: wars are expensive. 2. During the ‘50