第一篇：雙語教學比賽講稿：竇祥銘,安徽財經大學 經濟學院

Good afternoon, honorable judges, ladies and gentlemen, my name is Dou Xiangming, I come from the school of economics, today it is my greatest honor to have this opportunity to exchange my teaching experience with all of you here, and I wish to get your criticism and correction sincerely, thank you.In today’s class, we start to learn the fourth chapter: consumption and saving.消費和儲蓄作為重要的宏觀經濟變量，它們對宏觀經濟的整體運行具有重要的影響，因此對它們的分析和學習具有極為重要的理論及現實意義。

The chapter is divided by 2 sections.The first section includes consumption, and the consumption function and the propensity to consume.The second section includes saving, the saving function, and the propensity to save.我們先來看關于消費的內容。First of all, it’s the definition of consumption.In macroeconomics, consumption refers to a country or a region’s individual residence or family’s all expenditures on purchasing consumer goods and services in order to satisfy consuming desire in a fixed time.顯然，宏觀經濟學中的消費指的是總的消費。

Then, it’s the consumption function.The consumption function refers to the interdependent relationship between consumption and various factors that decide consumption.There are many factors influence consumption, such as the income level, the consumer price level, individual consumer ’s preference, consumer’s expectation of future income, consumer credit and it’s interest rate, etc, there is no doubt that the income level is the most important factor that influences consumption.消費函數指的是消費與決定消費的各種因素之間的相互依存的關系。影響消費的因素眾多，比如收入水平、消費品價格水平、消費者個人偏好、消費者對未來收入的預期、消費信貸及其利率等，但毫無疑問其中影響消費最重要的一個因素是收入水平。宏觀經濟學初級階段我們所學習的消費函數其實主要考慮的就2個因素，即作為自變量的收入水平和作為因變量的消費水平。

為更好地理解消費函數，我們有必要對消費函數的表達式及其圖像展開學習。首先來看消費函數的一般表達式及其圖像。In the graph above, vertical axis expresses the consumption level or C, horizontal axis expresses the income level or Y, we can see the consumption function curve slopes upward and becomes flatter.可見，圖像中的消費函數曲線是一條向右上方傾斜且愈發平緩的曲線，這條曲線很明顯地把消費函數的兩個重要屬性表示出來：一是隨著收入的增加，消費也會增加，用數學語言表示就是一階導數大于0；二是隨著收入的增加，消費增加的速率會下降，用數學語言表示就是二階導數小于0。

接著我們來看消費函數的線性表達式及其圖像。In liner expression of the consumption function, a is the autonomous consumption, bY is the induced consumption, b is the marginal propensity to consume.在消費函數的線性表達式中，a是自發性消費，即不受收入影響而相對穩定的消費；bY是誘致性消費，即會受收入影響而相對不穩定的消費；b是邊際消費傾向，還原為通俗語言，即每增加一個單位的收入，你會從中拿出多大的份額去用于消費。

邊際消費傾向不同國家之間的差異較大，其中的原因是多方面，在此我就不再給予贅述。如曾經一段時間中國的邊際消費傾向介于0.60—0.65之間，而同期美國的邊際消費傾向卻介于0.90—0.95之間。可見，中國人的邊際消費傾向大大小于美國人的邊際消費傾向，換言之，就是中國人更不愿意花錢。中國人花錢少，儲蓄就高，短期看不利于市場的發展，但中長期看卻能為社會擴大再生產積累起雄厚的資金；而美國人花錢多，儲蓄就低，短期看能帶動市場的發展，但中長期看卻會造成社會擴大再生產資金的不足。中國把通過高儲蓄積累起來的資金借給美國，因此成為目前美國最大的債主。

Finally, it’s the propensity to consume.The propensity to consume refers to the ratio of consumption to income, mainly including the average propensity to consume and the marginal propensity to consume.The average propensity to consume or APC refers to the ratio of total consumption to total income.根據定義，顯然有平均消費傾向APC = C / Y。The marginal propensity to consume or MPC refers to the ratio of consumption increment to income increment.根據定義，顯然有邊際消費傾向MPC=ΔC/ΔY , 當ΔC和ΔY趨向于極小值時，MPC= dC/dY。通過簡單的推導，我們能得出平均消費傾向APC＞邊際消費傾向MPC，具體推導過程我就不寫了，作為作業留給大家課下完成。

下面我們來看關于儲蓄的內容。Similar with consumption, first of all, it’s the definition of saving.In macroeconomics, saving refers to a country or a region’s individual residence or family’s all income that excludes the consumption in a fixed time.根據定義，宏觀經濟學中的消費強調的也是總的消費。中國國民儲蓄率很高，并且增長很快，傳統觀點認為主要原因在于中國的老百姓愛存錢，這點不假，但造成中國國民儲蓄率高的真正原因卻是相比老百姓，政府和企業更喜歡存錢，如1992—2012年，中國國民儲蓄率從35%上升到59%，但居民儲蓄率卻一直維持在20%的水平，可見，政府和企業對儲蓄更是“情有獨鐘”。

Then, it’s the saving function.The saving function refers to the interdependent relationship between saving and various factors that decide saving.There are many factors influence saving, such as the income level, wealth distribution, consuming habit, the structure of social security system, interest rate level, etc, there is no doubt that the income level is the most important factor that influences saving.儲蓄函數指的是儲蓄與決定儲蓄的各種因素之 間的關系。影響消費的因素眾多，如收入水平、財富分配狀況、消費習慣、社會保障體系的結構、利率水平等，但其中最重要的一個因素還是收入水平。

和消費函數的學習一樣，下面我們來學習儲蓄函數的表達式及其圖像。首先是儲蓄函數的一般表達式及其圖像。In the graph above, we can see the saving function curve slopes upward and becomes steeper.可見，圖像中的儲蓄函數曲線是一條向右上方傾斜且愈發陡峭的一條曲線，這條曲線很明顯地把儲蓄函數的兩個重要屬性表示出來：一是隨著收入的增加，儲蓄也會增加，用數學語言表示就是一階導數大于0；二是隨著收入的增加，儲蓄增加的速率會加大，用數學語言表示就是二階導數也大于0。

接著我們來看儲蓄函數的線性表達式及其圖像。In liner expression of the saving function,-a(minus a)is the autonomous saving,(1-b)Y(one minus b then times Y)is the induced saving, 1-b(one minus b)is the marginal propensity to save.在儲蓄函數的線性表達式中，-a是自發性儲蓄；(1-b)Y是誘致性儲蓄；1-b是邊際儲蓄傾向。結合前面關于消費函數的學習，我們能看出儲蓄函數與消費函數之間存在互補的關系，即知道其中一個函數，我們就能推出另外一個函數。

Finally, it’s the propensity to save.The propensity to save refers to the ratio of saving to income, mainly including the average propensity to save and the marginal propensity to save.The average propensity to save or APS refers to the ratio of total saving to total income.根據定義，顯然有平均儲蓄傾向APS = S / Y.The marginal propensity to save or MPS refers to the ratio of saving increment to income increment.根據定義，顯然有邊際儲蓄傾向MPS=ΔS/ΔY , 當ΔS和ΔY趨向于極小值時，MPS= dS/dY。通過簡單的推導，我們能得出平均儲蓄傾向APS＜ 邊際儲蓄傾向MPS，具體推導過程也是今天我留給大家的課下作業。

In the end, it’s the Chapter Summary 1.In macroeconomics, consumption or saving focus on the aggregate consumption or saving.（在宏觀經濟學中，消費或儲蓄強調的是總的消費或總的儲蓄。）

2.The income level is the most important factor that decides consumption or saving.（收入水平是影響消費和投資的最重要的一個因素。）

3.There is a complementary relationship between the consumption function and the saving function.（消費函數和儲蓄函數存在互補關系。）

4.APC﹥（is greater than）MPC, APS﹤（is lesser than）MPS, APC+(plus)APS=(equals)MPC+MPS=1.That is all, than you for your time and attention, see you next time, bye.