理解Utility效用in economy

• Utility

  From wikipedia, the concept of utility is used to model worth or value. Its usage has evolved significantly over time.

  The term was introduced initially as a measure of pleasure or satisfaction within the theory of utilitarianism by moral philosophers such as Jeremy Bentham and John Stuart Mill. The term has been adapted and reapplied within neoclassical economics, which deminates modern economic theory, as a utility function that represents a consumer’s preference ordering over a choice set.

  Utility has thus become a more abstract concept, that is not necessarily solely based on the satisfaction/pleasure received.

• Utility function

  Consider a set of alternatives facing an individual, and over which the individual has a preference ordering.

  A utility function is able to represent those preferences if it is possible to assign a real number to each alternative, in such a way that alternative a is assigned a number greater than alternative b if , and only if , the individual prefers alternative a to alternative b.

  In general economic terms, a utility function measures preferences concerning a set of goods and services.

  Often, utility is correlated with words such as happiness, satisfication, and welfare, and these are hard to measure mathematically. Thus, economists utilize consumption baskets of preferences in order to measure these abstract, non quantifiable ideas.

• Applications

  Utility is usually applied by economists in such constructs as the indifference curve, which plot the combination of commodities that an individual or a society would accept to maintain a given level of satisfaction.

  Utility and indifference curves are used by economists to understand the underpinnings of demand curves, which are half of the supply and demand analysis that is used to analyze the workings of goods markets.

  Indifference curve :

  From wikipedia, in economocs, an indifference curve connects points on a graph representing different quatities of two goods, points between which a cunsumer is indifferent.

• 总结

  效用（Utility）被经济学家用来度量满意度、开心等无法量化的概念。

  效用函数（Utility Function）用于表示主体为维持一定的满意度所需要的商品或服务，即x为商品或服务的数量，y为满意程度。