行為經濟學經典(英文版)(pdf 40頁)

Economics defines investment as the act of incurring an immediate cost in the
expectation of future rewards. Firms that construct plants and install equipment,
merchants who lay in a stock of goods for sale, and persons who spend time on
vocational education are all investors in this sense. Somewhat less obviously, a firm that shuts down a loss-making plant is also "investing": the payments it must make to extract itself from contractual commitments, including severance payments to labor, are the initial expenditure, and the prospective reward is the reduction in future losses.
Viewed from this perspective, investment decisions are ubiquitous. Your purchase of this book was an investment. The reward, we hope, will be an improved understanding of investment decisions if you are an economist, and an improved ability to make such decisions in the course of your future career if you are a business school student.
Most investment decisions share three important characteristics it varying degrees. First, the investment is partially or completely irreversible. In other words, the initial cost of investment is at least partially sunk; you cannot recover it all should you change your mind. Second, there is uncertainty over the future rewards from the investment. The best you can do is to assess the probabilities of the alternative outcomes that can mean greater or smaller profit (or loss) for your venture. Third, you have some leeway about the timing of your investment. You can postpone action to get more information (but never, of course, complete certainty) about the future.
These three characteristics interact to determine the optimal decisions of investors. This interaction is the focus of this book. We develop the theory of irreversible investment under uncertainty, and illustrate it with some practical applications.
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