Daily article 79: Understand and calculate GDP
Let’s continue our discussions in economics. Having talked about several important concepts in microeconomics, today let’s meet a very popular one in macroeconomics, gross domestic product (GDP). As you’ve known, macroeconomics studies aggregate quantities of a nation, among which GDP is probably the most commonly used one to represent a nation’s economic performance.
GDP measures the market value of all final goods and services produced within the economy in a given period of time. For example, the 2020 GDP of China measures the total market value of all final goods and services produced within China in 2020. Thus we can definitely calculate the GDP by counting all final goods and services, calculate their market value, and add them up. However, in real life counting those products and services involves many errors and can be too time-consuming. So we usually calculate GDP using other two major methods.
The first method is to use expenditure approach. Let’s just think about who will pay for all those goods and services. Intuitively, families, companies and governments will be the answers. But don’t forget we will buy some goods and services from other parts of world(import) and they will also buy from us(export). The net value(export-import) should be counted as GDP because it measures the net value of goods and services that foreigners buy while produced in our country. Therefore, we have GDP = C + I + G + (X-M), where C refers to customer, I refers to private domestic investment, G refers to Government spending, X refers to export and M refer to import.
We can also look at GDP from another perspective. Who will receive money for producing those goods and services? Workers receive salaries, companies receive profits, governments receive taxes(but they pay out subsidies), banks and other money providers receive interest, proprietors also receive income, land providers receive rent. Besides that, we also need to consider depreciation. Imagine that companies have lots of machines and they need to spend some of the their income to offset the depreciation before profit in order to maintain the same level of productivity. In consequence, using the income approach we have GDP = Compensation of employees + Corporate and government enterprise profits before taxes + Interest income + Proprietor’s income + Rent + Indirect business taxes less subsidies + Depreciation.
让我们继续关于经济学的话题。之前我们介绍了微观经济学中的一些重要概念，今天，让我们看看宏观经济学的一个重要概念：国民生产总值（GDP）。你已经知道宏观经济学主要研究一个国家的经济总量，而GDP则是最常见的用于衡量一个国家经济表现的指标。
GDP衡量一个经济体在一个特定时间内生产的最终产品和服务的总的市场价值。比如，中国2020年的GDP就是指中国在2020年内生产的最终产品和服务的市场价值总和。因此，我们可以很直接地去统计生产了多少最终产品和服务，计算每一项的市场价值，然后加总得出GDP。然而在现实生活中，这种方法统计的过程中可能会有很大误差，也非常耗时，所以我们一般采取另外两种办法。
一种是支出法。让我们想想，究竟是谁会购买这些最终产品和服务。自然而然地，我们会想到家庭，公司和政府。但别忘了，我们也在从世界其他地方买东西（进口），他们也同时从我们这里购买（出口）。所以净出口（出口减进口）应该被统计进GDP因为它衡量了别人购买的我们国家生产的最终产品和服务的净值。因此，我们有一个公式
GDP =家庭消费 + 企业投资 + 政府购买 + （出口-进口）。我们也可以从另一个角度看待GDP。哪些人会在生产最终产品和服务中收到钱呢？工人会收到薪水，企业获得利润，政府获得税收（但同时也会支出补贴），银行和其他的资本提供者收到利息，非企业所有者（个体户）也会有收入，土地提供者收取租金。除了以上这些之外，我们也要考虑折旧。想象一下企业有很多机器，而他们要把收入的一部分用于抵消这些折旧，以保证同样水平的生产能力，然后才能计算利润。总结一下，我们应用收入法又有了一个公式：
GDP = 劳动者报酬 + 民营和国营企业税前利润 + 利息收入 + 非企业所有者收入 + 租金 + （非直接商业税-政府补贴）+ 折旧。
