Elasticity is a term used a lot in economics todescribe the way one thing changes in a givenenvironment in response to another variable thathas a changed value.
For example, the quantity of a specific product soldeach month changes in response to themanufacturer alters the product's price.
例如，每個月銷售的特定產品的數量隨著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 elasticitymeasures the responsiveness of one variable in a given environment to a change in anothervariable, which in this instance is a change in price.
更為抽象的說法，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 demandvaries 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系取決于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 consumerdemand should diminish.
當制造商大幅度提高產品價格時，消費者的需求就會減少，這不足為奇。
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 alittle, some shoppers might stay loyal to the specific brand -- at one time, Bayer nearly had alock on the U.S. aspirin market -- but many more consumers would probably seek the sameproduct from another manufacturer at the lower price.
In such instances, the demand for the product is highly elastic and such instances e conomistsnote 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, thedemand for the product may continue even as the price rises -- basically, because the consumerhas no alternative.
Another strange phenomenon in price/demand elasticity in the 21st century has to do withthe 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 arenot directly responsive to demand, but rather to the ways consumers order the product -- aproduct that cost X when initially ordered may be filled at X-plus when reordered, often whenthe consumer has initiated automatic re-ordering.
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 algorithmicestimation of some future demand, not a demand that actually exists when the price ischanged.
Some travel sites, USA and others have noted, put a cookie on the consumer's computer whenthe consumer first inquires about the cost of a product; when the consumer checks again, thecookie raises the price, not in response to a general demand for the product, but in responseto a single consumer's expression of interest.
These situations do not at all invalidate the principle of price elasticity of demand. Ifanything, they confirm it, but in interesting and complicated ways.
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 ofsources 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 anyproduct 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 waysthat 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 itsown variables. In this introductory article, we've briefly surveyed the concept of the priceelasticity of demand. Here's the formula:
