双语教学比赛讲稿：consumption and saving. 消费和储蓄

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.消费和储蓄作为重要的宏观经济变量，它们对宏观经济的整体运行具有重要的影响，因此对它们的分析和学习具有极为重要的理论及现实意义。

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.

我们先来看关于消费的内容。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. 显然，宏观经济学中的消费指的是总的消费。

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. 消费函数指的是消费与决定消费的各种因素之间的相互依存的关系。影响消费的因素众多，比如收入水平、消费品价格水平、消费者个人偏好、消费者对未来收入的预期、消费信贷及其利率等，但毫无疑问其中影响消费最重要的一个因素是收入水平。宏观经济学初级阶段我们所学习的消费函数其实主要考虑的就2个因素，即作为自变量的收入水平和作为因变量的消费水平。

为更好地理解消费函数，我们有必要对消费函数的表达式及其图像展开学习。首先来看消费函数的一般表达式及其图像。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. 可见，图像中的消费函数曲线是一条向右上方倾斜且愈发平缓的曲线，这条曲线很明显地把消费函数的两个重要属性表示出来：一是随着收入的增加，消费也会增加，用数学语言表示就是一阶导数大于0；二是随着收入的增加，消费增加的速率会下降，用数学语言表示就是二阶导数小于0。

接着我们来看消费函数的线性表达式及其图像。In liner

expression of the consumption function, a is the autonomous consumption, bY is the induced consumption, b is the marginal propensity to consume. 在消费函数的线性表达式中，a是自发性消费，即不受收入影响而相对稳定的消费；bY是诱致性消费，即会受收入影响而相对不稳定的消费；b是边际消费倾向，还原为通俗语言，即每增加一个单位的收入，你会从中拿出多大的份额去用于消费。

边际消费倾向不同国家之间的差异较大，其中的原因是多方面，在此我就不再给予赘述。如曾经一段时间中国的边际消费倾向介于0.60—0.65之间，而同期美国的边际消费倾向却介于0.90—0.95之间。可见，中国人的边际消费倾向大大小于美国人的边际消费倾向，换言之，就是中国人更不愿意花钱。中国人花钱少，储蓄就高，短期看不利于市场的发展，但中长期看却能为社会扩大再生产积累起雄厚的资金；而美国人花钱多，储蓄就低，短期看能带动市场的发展，但中长期看却会造成社会扩大再生产资金的不足。中国把通过高储蓄积累起来的资金借给美国，因此成为目前美国最大的债主。

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. 根据定义，显然有平均消费倾向APC = C / Y。The marginal propensity to consume or MPC refers to the ratio of consumption