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.
讓我們繼續關於經濟學的話題。之前我們介紹了微觀經濟學中的一些重要概念，今天，讓我們看看宏觀經濟學的一個重要概念：國民生產總值（GDP）。你已經知道宏觀經濟學主要研究一個國家的經濟總量，而GDP則是最常見的用於衡量一個國家經濟表現的指標。
GDP衡量一個經濟體在一個特定時間內生產的最終產品和服務的總的市場價值。比如，中國2020年的GDP就是指中國在2020年內生產的最終產品和服務的市場價值總和。因此，我們可以很直接地去統計生產了多少最終產品和服務，計算每一項的市場價值，然後加總得出GDP。然而在現實生活中，這種方法統計的過程中可能會有很大誤差，也非常耗時，所以我們一般採取另外兩種辦法。
一種是支出法。讓我們想想，究竟是誰會購買這些最終產品和服務。自然而然地，我們會想到家庭，公司和政府。但別忘了，我們也在從世界其他地方買東西（進口），他們也同時從我們這裡購買（出口）。所以淨出口（出口減進口）應該被統計進GDP因為它衡量了別人購買的我們國家生產的最終產品和服務的淨值。因此，我們有一個公式
GDP =家庭消費 + 企業投資 + 政府購買 + （出口-進口）。我們也可以從另一個角度看待GDP。哪些人會在生產最終產品和服務中收到錢呢？工人會收到薪水，企業獲得利潤，政府獲得稅收（但同時也會支出補貼），銀行和其他的資本提供者收到利息，非企業所有者（個體戶）也會有收入，土地提供者收取租金。除了以上這些之外，我們也要考慮折舊。想象一下企業有很多機器，而他們要把收入的一部分用於抵消這些折舊，以保證同樣水平的生產能力，然後才能計算利潤。總結一下，我們應用收入法又有了一個公式：
GDP = 勞動者報酬 + 民營和國營企業稅前利潤 + 利息收入 + 非企業所有者收入 + 租金 + （非直接商業稅-政府補貼）+ 折舊。
