經濟學中的彈性是什麼?

Elasticity is a term used a lot in economics to describe the way one thing changes in a given environment in response to another variable that has a changed value.

彈性是經濟學中經常使用的一個術語，用來描述在給定環境中一個變量相對於另一個變量發生一定比例改變的屬性。

For example, the quantity of a specific product sold each month changes in response to the manufacturer alters the product's Price.

例如，每個月銷售的特定產品的數量隨着廠商改變產品的價格而變化。

A more abstract way of putting it that means pretty much the same thing is that elasticity measures the responsiveness of one variable in a given environment to a change in another variable, which in this instance is a change in price.

更爲抽象的說法，彈性衡量的是給定環境中一個變量對另一個變量變化的響應性，在這個例子中是價格變化。

Or you could also say it measures "the sensitivity" of that variable.

或者你也可以說它測量了這個變量的“靈敏度”。

Often, e conomists speak of a demand curve, where the relationship between price and demand varies depending upon how much or how little one of the two variables is changed.

通常，經濟學家說的是需求曲線，即價格和需求之間的關係取決於兩個變量中的一個變化了多少。

Some Examples of Elasticity and Inelasticity

彈性和非彈性的一些例子

It's not surprising when a manufacturer substantially increases a product's price, that consumer demand should diminish.

當製造商大幅度提高產品價格時，消費者的需求就會減少，這不足爲奇。

Many common items, such as aspirin, are widely available from any number of sources.

許多常見物品，如阿司匹林，可以從許多來源廣泛獲得。

In such cases, the product's maker raises the price at its own risk -- if the price rises even a little, some shoppers might stay loyal to the specific brand -- at one time, Bayer nearly had a lock on the U.S. aspirin market -- but many more consumers would probably seek the same product from another manufacturer at the lower price.

在這種情況下，廠商提高價格就會有自己的風險——如果價格小幅上漲，一些消費者可能仍然會忠於特定的品牌——拜耳一度幾乎佔有了美國阿司匹林市場——但是更多的消費者可能會以較低的價格從其他廠商那裏尋找相同的產品。

In such instances, the demand for the product is highly elastic and such instances e conomists note a high sensitivity of demand.

在這種情況下，對產品的需求是高度彈性的，經濟學家注意到了需求的高度敏感性。

But in other instances, the demand is not elastic at all.

但在其他情況下，需求根本不具有彈性。

Water, for example, is usually supplied in any given municipality by a single quasi-governmental organization, often along with electricity.

例如，在任何特定的城市，水通常由一個單一的準政府組織供應，通常與電力一起供應。

When something consumers use daily, such as electricity or water, has a single source, the demand for the product may continue even as the price rises -- basically, because the consumer has no alternative.

當消費者日常使用的東西（比如電或水）只有唯一一個來源時，即使價格上漲，對產品的需求也還是會繼續的，因爲消費者們基本沒有其他選擇。

Interesting 21st Century Complications

有趣的21世紀併發症

Another strange phenomenon in price/demand elasticity in the 21st century has to do with the Internet.

21世紀價格/需求彈性的另一個奇怪現象與互聯網有關。

The New York Times has noted, for instance, that Amazon often changes prices in ways that are not directly responsive to demand, but rather to the ways consumers order the product -- a product that cost X when initially ordered may be filled at X-plus when reordered, often when the consumer has initiated automatic re-ordering.

例如，《紐約時報》指出，亞馬遜經常以不直接響應需求而是響應消費者訂購產品的方式來改變價格——某種產品首次訂購時成本爲X，當消費者開始主動回購時，再次訂購時的成本就變爲X+了。

The actual demand, presumably, hasn't changed, but the price has.

實際需求可能沒有發生變化，但是價格已經改變了。

Airlines and other travel sites commonly change the price of a product based on an algorithmic estimation of some future demand, not a demand that actually exists when the price is changed.

航空公司和其他旅遊網站通常會根據對未來需求的估計來改變產品價格，而不是依據價格改變時實際存在的需求。

Some travel sites, USA and others have noted, put a cookie on the consumer's computer when the consumer first inquires about the cost of a product; when the consumer checks again, the cookie raises the price, not in response to a general demand for the product, but in response to a single consumer's expression of interest.

美國和其他一些旅遊網站指出，當消費者首次查詢產品的價格時，會在消費者的電腦上儲存一個cookie；當消費者再次查看時，cookie會提高價格，這不是反映產品的普遍需求，而是反映了單個消費者的興趣。

These situations do not at all invalidate the principle of price elasticity of demand. If anything, they confirm it, but in interesting and complicated ways.

這些情況根本不會使需求的價格彈性原則失效。如果說有什麼不同的話，那就是他們以有趣而複雜的方式證實了這一點。

In summary:

綜上所述：

Price/demand elasticity for common products is generally high.

普通產品的價格/需求彈性通常很高。

Price/demand elasticity where the good has only a single source or a very limited number of sources is typically low.

當商品只有單一來源或來源數量非常有限時，價格/需求彈性通常很低。

External situations may create rapid changes in the price elasticity of demand for almost any product with low elasticity.

外部環境可能會導致幾乎所有低彈性產品的需求價格彈性的快速變化。

Digital capabilities, such as "demand pricing" on the Internet, can affect price/demand in ways that were unknown in the 20th century.

數字能力，例如互聯網上的“需求定價”，可以以20世紀未知的方式影響價格/需求。

How to Express Elasticity as a Formula

如何用公式表達彈性

Elasticity, as an economics concept,can be applied to many different situations, each with its own variables. In this introductory article, we've briefly surveyed the concept of the price elasticity of demand. Here's the formula:

彈性，作爲一個經濟學概念，可以應用到許多不同的情況，每種情況都有自己的變量。在這篇文章中，我們簡要介紹了需求價格彈性的概念。以下是需求價格彈性的公式:

Price Elasticity of Demand (PEoD) = (% Change in Quantity Demanded/ (% Change in Price)

需求價格彈性( PEoD ) = ( 需求量變化的百分比/ (價格變化的百分比)