布兰查德 宏观经济学 第16章.pptVIP

凯恩斯消费理论的回顾 凯恩斯消费理论的回顾（传统的消费理论） K’s消费理论的推论 边界消费倾向只很大，消费与收入具有同样强度的波动性 所描述的消费者只考虑眼前，目光短浅（非理性） 有关消费的更多的经验事实 现代消费理论的核心：消费者是理性的。既考虑现在也考虑将来。希望维持消费的平稳（生活标准不剧烈变动） 假定今年起活100年，今年收入为Ynow，以后每年的收入为Ylater。如果你是理性的消费者，如何安排每年的消费？ 如果今年收入提高1000元，每年消费提高多少？相应的边际消费倾向称为短期***，为多少？ 如果今年和以后每年都提高1000元，消费提高多少？长期边际消费倾向为多少？ 你的结论和上面的图相比较，结果如何？ 结论： 消费对收入短期波动反应不大，对收入长期的变动反应大。 消费比较平稳。 Consumption The theory of consumption was developed by Milton Friedman in the 1950s, who called it the permanent income theory of consumption, and by Franco Modigliani, who called it the life cycle theory of consumption. The Very Foresighted Consumer A very foresighted consumer who decides how much to consume based on the value of his total wealth, which comprises: The value of his nonhuman wealth, or the sum of financial wealth and housing wealth. The value of his human wealth and nonhuman wealth together gives an estimate of his total wealth. An Example Building on what you saw in Chapter 14, let’s compute the present value of your labor income as the value of real expected after-tax labor income, discounted using real interest rates. Your wealth today, the expected value of your lifetime after-tax labor income, is around $2 million. Toward a More Realistic Description The constant level of consumption that a consumer can afford equals his total wealth divided by his expected remaining life. Consumption depends not only on total wealth but also on current income. Toward a More Realistic Description In words: Consumption is an increasing function of total wealth, and also an increasing function after-tax labor income. Total wealth is the sum of nonhuman wealth – financial wealth plus housing wealth – and human wealth – the present value of expected after-tax income. Putting Things Together: Current Income, Expectations, and Consumption Expectations affect consumption in two ways: Directly through human wealth, or expectations of future labor income, real interest rates, and taxes. Indirectly through nonhuman w