Economics 314 Coursebook, 2009 Jeffrey Parker 15 THEORIES OF INVESTMENT EXPENDITURES Chapter 15 Contents A. Topics and Tools ..............................................................................2 B. How Firms Invest ............................................................................2 What investment is and what it is not ............................................................................ 2 Financing of investment ................................................................................................ 3 The Modigliani-Miller theorem ..................................................................................... 5 Sources of finance and credit availability effects ............................................................... 6 C. Investment and the Business Cycle ...................................................... 8 Keynes and the business cycle ........................................................................................ 8 The accelerator theory of investment ............................................................................... 9 The multiplier-accelerator model .................................................................................. 10 D. Understanding Romer’s Chapter 8 ..................................................... 12 The firm’s profit function ............................................................................................ 13 User cost of capital ...................................................................................................... 14 Adjustment-cost model ................................................................................................ 15 Tobin’s q ................................................................................................................... 17 Average and marginal q .............................................................................................. 17 Dynamic analysis ....................................................................................................... 18 E. Empirical Studies of Investment .......................................................... 19 Empirical evidence on the acceleration principle ............................................................ 20 Empirical testing of the neoclassical model .................................................................... 24 Empirical specification of adjustment costs and q models ................................................ 29 Empirical results using average q ................................................................................. 32 Alternative strategies for estimating the adjustment-cost model ........................................ 35 Using tax reforms as natural experiments ...................................................................... 37 Imperfect capital markets: Cash flow and related variables.............................................. 38 Effects of irreversibility, uncertainty, and non-convex adjustment costs ............................. 43 F. Works Cited in Text ....................................................................... 47 15 – 2 A. Topics and Tools Investment expenditures play a key role in many theories of the business cycle, in-cluding Keynes’s theory. Macroeconomic theorists have agreed on a basic framework that models the investment strategy of a profit-maximizing firm. However, empirical evidence has failed to provide substantial support for this model, which has been a source of frustration for those involved in investment modeling. In this chapter, we will investigate some of the details of the investment process, in-cluding how firms raise the funds they use for investment, how models of the various kinds of investment differ, and how financial markets affect investment expenditures. The Romer text develops the model in the form known as the q theory of invest-ment. This is based on a measure of the desirability of investment known as Tobin’s q. The q theory is easily reconciled with other approaches to investment, all of which lead to the same basic result. B. How Firms Invest What investment is and what it is not The term “investment” means something different to economists than it does to most of the rest of the world. For example, if you ask your banker about investment, she will probably start talking about stocks and mutual funds that she would like you to pur-chase, or new kinds of deposit accounts that her bank offers. To an economist, these purchases of financial assets are not investment from a social point of view because fi-nancial assets do not represent real net wealth for the economy as a whole. Instead, they reflect credit relationships within the economy. Financial assets such as loans and bank accounts represent contracts to pay interest and repay principal on borrowed money. Stocks represent partial ownership of a corporation, implying a right to vote on the go-vernance of the corporation and to receive dividends as determined by the directors that the shareholders elect. In either case, the financial asset of one individual in the econo-my is offset by a financial liability of another person or corporation. Thus, when we ag-gregate the wealth of all members of the economy, these assets and liabilities cancel and financial assets disappear. Thus, if you “invest” in a financial asset, someone else is “dis-investing” at the same time, so aggregate, or social, investment does not rise. Economists usually reserve the term investment for transactions that increase the magnitude of real aggregate wealth in the economy. This includes mainly the purchase15 – 3 (or production) of new real durable assets such as factories and machines.1 The category of investment that receives the most attention is business fixed investment, which is the purchase of new structures and equipment by business firms for production purposes. However, there are two other categories, and they are also important. Inventory investment consists of increases in stocks of unsold goods or unused input materials. This kind of investment is quite different from business fixed investment be-cause inventory capital normally has a very short life span. When inventories decrease from one period to the next, as sometimes happens even at an aggregate level, inventory investment is negative. Another unique feature of inventory investment is that it often occurs unintentionally. Unsold