In the American economy,millions of consumers make millions of decisions every day.You decide to buy a movie ticket instead of a paperback novel. Your roommate decides to buy 2 pounds of imported cheese rather than 1 pound or 3 pounds.How do people make these decisions?
Economists have constructed a simple theory of consumers choice based on the hypothesis that each consumer spends his or be a reasonable starting point,since it says little more than that people do what they prefer.To make the theory operational,we need a way to measure utility.
A century ago, economists envisioned utility as an indicator of the pleasure a person derives from consuming some set of goods,and they thought that utility could be measured directly in some kind of psychological units(sometimes called utils)after somehow reading the consumer's mind.Gradually, they came to realize that this was an unnecessary and,perhaps,impossible task.How many utils did you get from the last movie you saw? You probably cannot answer that question because you have no idea what a util is. Neither does anyone else.
But you may be able to answer a different question like,"How many hamburgers would you give up to get that ticket?"If you answer"three",no one can say how many utils you get from seeing a film, but they can that you get more from the movie than from a single hamburger.When economists approach the issue in this manner, hamburgers,rather than utils,become the unit of measurement. They can say that the utility of a movie (to you) is three hamburgers.
Early in the 20th century concluded that this indirect way of measuring utility gave all they needed to build a theory of consumer choice. One can measure the utility of a moive ticket by asking how much of some other commodity (like hamburgers)you are willing to give up for it. Any commodity will do for this purpose,but the simplest choice,and the one that we will use in this book,is money.
參考答案:在美国这个国家，每天有成千上万的消费者在做决定。你决定买一张电影票而不是一本平装小说。你室友决定买2磅进口奶酪而不是1磅或者3磅。人们是怎样做这些决定了。
经济学家已经建立一个简单的消费者作出选择的理论。他们假设消费者是基于一个合理的出发点，而不是侧重于他们的喜好。为了使这个理论可行，我们需要一种方式来测试这个理论的效用。
一个世纪前，经济学家预想有效性作为一种人们从消费某些商品中获得乐趣的指标，并且他们认为通过解读消费者的心理，有效性可以直接用某种心理单元来测量（有时叫单位效用）。渐渐地，他们意识到这是一项不必要并且不可能的任务。你从你刚看的那部电影中获得多少单位效用？你可能不能回答，因为你根本不知道什么是单位效用。其他人也不知道。
但是你可能可以回答其他问题，如：你要放弃多少个汉堡才能买一张票？ 如果你回答，3个。没人能说你看电影获得多少单位效用，但他们能说你看电影得到的单位效用比一个汉堡多。当经济学家用这种方式来看问题时，汉堡成了测量效用的单位，而不是刚刚提到的单位效用。他们能说你看电影得到的效用是3个汉堡。
早在20世纪，这种间接测量效用的发式为建立消费者选择理论提供了所有依据。你可以通过询问为看场电影愿意放弃多少其他商品（如汉堡）来测量电影的效用。任何其他商品都是为这个目的，但我们这本书中最简单选择了钱作为指标。
