3 C H A P T E R C H E C K L I S T 學習本章後，您將能： 區別自發性支出與誘發性支出的差異，並解釋實質 GDP 的波動對支出計畫的影響1解釋實質 GDP 如何調整而達成均衡支出2描述與解釋支出乘數3由均衡支出推衍 AD 曲線4
4 充分就業的經濟 回顧與前瞻 在充分就業下，實質 GDP 等於 GDP 潛能，失業率等於自然失業率 If you want to talk about Keynes and his contribution to economics, this is probably the best place to do it. A Keynes biographical sketch can be found at The aggregate expenditure model, presented in this chapter, is the essence of Keynes General Theory. Don Patinkin, a leading historian of economic thought and Keynes scholar, said that the innovation of the General Theory was to replace price with income (GDP) as the equilibrating variable. This version of the model cannot be found in the General Theory, mainly because Keynes was writing before the national income accounting system had been developed. So he made up his own aggregates, based on employment and a money wage measure of the price level. But the words and equations of the General Theory can be translated readily into the textbook version of the model. This version of the model first appeared in The Elements of Economics, a textbook authored by Lorie Tarshis published in It was popularized by Paul Samuelson in the first edition of his celebrated text published in 1948.
5 偏離充分就業 回顧與前瞻 總合供給與總合需求決定均衡實質 GDP 與物價水準 總合供給與總合需求的變動則造成經濟在充分就業上下的波動 本章將介紹導致總合需求變動的因素
6 回顧與前瞻物價水準固定在總合支出模型中，假設物價水準固定不變該模型解釋：物價固定下實質 GDP 需求量的決定因素
7 30.1 支出計畫與實質 GDP 所得與支出循環流量模型顯示總合支出等於： 消費支出 C 投資 I 政府支出 G 淨出口 NX
8 計畫與非計畫支出 30.1 支出計畫與實質 GDP 總合計畫支出 為消費支出計畫、政府支出計畫、投資與庫存計畫及淨出口計畫的總和
9 30.1 支出計畫與實質 GDP 如果總合計畫支出等於實質 GDP，則廠商的庫存等於支出計畫的庫存
10 30.1 支出計畫與實質 GDP 實際支出等於計畫支出加上廠商非計畫的庫存變動，又等於實質 GDP 與總所得 廠商非計畫中的庫存變動導致生產與所得的變動，如果非計畫中的庫存增加，則廠商減少生產，於是實質 GDP 下降如果非計畫中的庫存減少，則廠商增加生產，於是實質 GDP 上升
33 均衡的收斂 30.2 支出計畫與實質 GDP 在均衡支出下，生產計畫等於支出計畫 但是，當總合計畫支出與實際總合支出不相等時，生產計畫與支出計畫不平衡，於是收斂至均衡支出的過程開始進行
34 乘數 是指自發性支出變動 ( 例如投資 ) 所引起實質 GDP 變動量，為自發性支出變動量的倍數 30.3 支出乘數當投資增加，則總合支出與實質 GDP 皆增加 ，但實質 GDP 的增加量大於投資的增加量乘數 是指自發性支出變動 ( 例如投資 ) 所引起實質 GDP 變動量，為自發性支出變動量的倍數There are several ways to approach the derivation of the multiplier. The most accessible way to launch your lecture is allow students to “get their hands dirty” by performing a couple of quick calculations. Ask your students to assume that your classroom is a small city and that you are interested in building a brand new factory there. Assume that the initial expenditure will be $100 million. Pretend to write out a check to the first general contractor (a student in the first row). This contractor will pay the workers, the next student. (You can explain to the class that you are assuming everything is constructed using only labor for simplicity. Nothing changes except adding complications if you take account of intermediate inputs.) Ask the class to assume that everyone’s marginal propensity to consume is 0.9. So the first worker will spend $90 million in total. You can either ask the stuChapter dent what he or she would buy or you can suggest an item, such as cars. In any case, the student spends the income by handing it to the very next student, who, coincidentally manufactures cars or whatever the student buys. So the $90 million in expenditure is income to the next student who, in turn, will spend $81 million. You can continue these rounds as spending through as many iterations as you want. But, regardless of the number, have the class keep a running tally of all the spending and income that is created from the initial expenditure.[Continued on next slide]
35 乘數的基本觀念 30.3 支出乘數 原先的投資增加引起總合支出的增加量大於原先投資的增加量 乘數決定總合支出變動量的幅度 Now ask if this process will ever come to an end. A bright math student might argue that the process never really comes to an end because what you have here is an infinite geometric series. Make sure to compliment the student’s insight but explain that the process does come to an end because the series converges. That is, at some point the income that will be generated for the next person will become arbitrarily close to zero. Explain to your students that what they have just witnessed is the multiplier. Once they see this demonstration, the multiplier becomes quite intuitive!
51 由均衡支出推衍 AD 曲線 30.4 AD 曲線與均衡支出 AE 曲線代表總合計畫支出與實質 GDP 的關係 實質 GDP 的變動引起沿著 AE 曲線上的移動AD 曲線代表實質 GDP 需求量與物價水準的關係物價水準變動引起沿著 AD 線上的移動Even though the aggregate demand curve is only mentioned in section 30.4, where it is derived, nonetheless students often get the aggregate demand curve and aggregate expenditure curve confused or, worse yet, believe that they both mean the same thing. As a way to help your students avoid some dangerous pitfalls, it can be worth talking about the difference between the two. Explain that the aggregate expenditure model is a fixed price model that examines how aggregate expenditure depends on disposable income. The aggregate demand curve, however, is a variable price model that examines how aggregate demand depends on the price level. Keep in mind that the decision whether to assign Checkpoint 30.4, the derivation of the AD curve, is up to you. This derivation is by no means necessary for students to obtain a good grasp of aggregate expenditure, aggregate demand, and the important issues that surround business cycle fluctuations