کار مفید و اطلاعات به عنوان محرک های رشد اقتصادی
|کد مقاله||سال انتشار||تعداد صفحات مقاله انگلیسی||ترجمه فارسی|
|13049||2012||10 صفحه PDF||سفارش دهید|
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Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Ecological Economics, Volume 73, 15 January 2012, Pages 93–102
A semi-empirical endogenous growth theory was proposed by the authors in 2005. It is based on a model of the economy as a two-stage materials/energy processing system. Growth is simulated by a two-parameter production function with two traditional factors, labor and capital, and a non-traditional factor, namely ‘useful work’. The non-traditional factor is calculated from primary energy inputs multiplied by an empirically estimated average energy conversion efficiency, which is a function of changing technology over time. This model ‘explains’ past US growth from 1900 through 1973–74 with satisfactory accuracy but it slightly underestimates subsequent growth (i.e. it leaves a small unexplained but increasing residual) for the period after 1975. However, by subdividing capital stock into traditional and ICT components, we are able to extend the theory to explain US economic growth accurately. In this paper we also extend the results to Japan. The revised production function has only three independent parameters. The new model also has implications for future economic growth, energy and environmental policy that differ significantly from the traditional growth theory. These implications are discussed briefly.
This paper is about explanations of economic growth, with special reference to the role of energy and information and communication technologies (ICT). A semi-empirical endogenous growth theory was proposed by the authors in an earlier paper (Ayres and Warr, 2005), wherein growth is simulated by a two-parameter production function with two traditional factors, labor and capital, and a non-traditional factor, namely ‘useful work’. The non-traditional factor is calculated from primary energy inputs multiplied by an empirically estimated average energy conversion efficiency, which is a function of technology and time.1 The resulting time series of useful work for the US was used to reproduce output growth using a production function of capital, labor and useful work using the LINEX function with useful work as a third factor, and parametric fits determined econometrically (Ayres and Warr, 2005). The results provide a fairly satisfactory fit to real GDP for the period 1900–1975, but the fit is not so good after that time. In other words, after 1975, the US economy grew faster than any of the three factors. While the focus of our original model was on the role of the improving efficiency of energy conversion technologies, we accept the proposition that observed improvements derive from flows of ideas from an increasing stock of useful knowledge (Warr and Ayres, 2006). We argue that not all knowledge and derived technologies are equal and that those pertaining to energy productivity provide the greatest productivity enhancements and spillover potential. We suggest that the most promising means of measuring the impact of increased knowledge about energy conversion is through an economy wide evaluation of the aggregate energy (exergy) to useful work efficiency. As a result we choose to use a quantifiable output measure of implemented efficiency–productivity improvements as opposed to an immeasurable input — the productivity potential of a stock of (recombinant) ideas and the allocation of resources to ensure their development which can only poorly reflect the real value of intangibles such as experience, competence and know-how2 (Weitzman, 1998). We suspect that future economic growth will be increasingly driven by information and communications technologies (ICT). In this paper we test the hypothesis that ICT inputs might account for the growing discrepancy between actual and predicted GDP using the model. The role of capital is modified to distinguish traditional physical capital (machines, structures, objects) from ICT capital. We find that with differentiation of ICT capital stock and inclusion into the LINEX production function as a 1st order approximation improves the quality of the historical estimates of GDP. Importantly, the marginal productivities of the factors of production differ markedly from their costs shares in the national accounts with capital taking the lions share, useful work much of the remainder and labor only a very small fraction. The following Section 2 provides an introduction and review of the state of growth theory since the 1950s along with various efforts to deal with faults and gaps in the standard theory, mainly the absence of energy, and the laws of thermodynamics. This seems appropriate, inasmuch as to justify our approach we need to understand the historical reasons for that disconnect. The next Section 3 deals with the thermodynamic inputs to the new theory and discusses our view of the economy as a materials–energy–information processing system. Section 4 discusses the proposed modification to incorporate a role for information/communications technology (ICT) in our previous version of growth theory. Section 5 summarizes the empirical results of the modification. Section 6 discusses implications and offers responses to the usual criticisms.
نتیجه گیری انگلیسی
A skeptical reader may accept that the results shown here reproduce the long-term trend but fail as an acceptable model of growth because tests on the residuals reveal the presence of (serial) autocorrelation and unit root behavior. Success in such tests is said (by some) to be required to validate the model. However we note that such tests are not well suited as a means of assessing time series models when input data to the model is estimated as a time average, as we have had to do with regard to useful work. Inclusion of time averaged data in the model introduces serially correlated error into the residuals. A further remark is appropriate here. A practical difficulty, and the reason for time averaging, is that many of the efficiency data needed for the theory are not compiled or published by any government agency. This, in turn, is because useful work (in the physical sense), is not a well-defined commodity that is produced by a defined sector and sold to other sectors. Electric power produced by central stations (electric utilities) is the single exception to this rule. In this case both inputs and outputs are recorded and published annually in the US by the Federal Power Commission and the US Department of Energy, and internationally by the IEA. The conversion efficiency in this case is easily calculated. It is unfortunate that comparable data for other (non-electric) forms of useful work are not routinely collected and published at present on an annual basis. Provision of such year-to-year data would remove the serial correlation from the useful work input time series, having a positive impact to reduce (serial) autocorrelation in the error residuals. While the calculations are undoubtedly flawed because the historical data are incomplete and imperfect, they were done as carefully as we know how. Of course, someone, someday, will do it better. However, the persistent skeptic could argue that, after all, our efficiency trend is a direct consequence of technological progress, itself a result of growth, hence is really not a conceptual improvement over the Solow residual. Why, she may well ask, is our technical conversion efficiency trend any more ‘endogenous’ than Solow's multiplier? The answer, as before, is two-fold. First, we argued a priori that efficiency is an important driver of growth, not the other way around. Second, we calculated the efficiency trend directly from historical data on energy (exergy) consumption and estimated conversion efficiencies, not indirectly by working back from GDP and an assumed production function. We have also identified bi-directional causality between output growth and useful work consumption the result of feedback between them ( Warr and Ayres, 2010). We therefore assume, of course, that historical gains in efficiency were endogenous, but what matters is whether future efficiency gains are automatic or not. We reckon that future gains depend upon human choice, as reflected in R&D and other government policies, but that they are by no means certain to occur. The next skeptical comment could be that our construction does not constitute a truly endogenous theory of growth because we have not postulated an explicit economic mechanism to explain the technological progress implicit in the efficiency trends. Here the skeptic is on slightly firmer ground. It is true, for instance, that we cannot explain in purely economic terms why the efficiency of electric power generation has increased so much more rapidly than the efficiency of space heating or automotive engines, as neither of those has increased significantly in the past 50 years. Several explanations are feasible, but we do not attempt to explain this phenomenon here. However, we do assert that technological progress in the real world does not occur uniformly and smoothly across all sectors, as it would if technological progress were truly exogenous. We could even remark that the spillovers from increased efficiency and reduced costs of electric power generation have undoubtedly been far greater than any imaginable spillovers from more efficient insulation. But such comments are really beside the point. The essential point is that we calculated the efficiency trend first, from real technical (and historical) data, whereas the Solow residual is still unexplained. The next and most troublesome criticism is probably the following: “Are you really saying that the only technologies that contribute to economic growth are technologies that increase the efficiency of exergy conversion? You are suggesting, for instance, that medical technologies do not contribute to economic growth, even though such spectacular progress has been made in conquering disease”. The answer to that is a firm yes and no. Yes, we do, in fact, suggest that improved health services – along with other labor-intensive services – add little directly to measurable growth, accepting that people living longer and more healthy lives arguably has an indirect impact on GDP. They suffer from what has been called the Baumol disease (Kander, 2005 and Kander and Henriques, 2010). Inputs to health services, as well as education, government, finance and other services, are mostly labor, and it is difficult to measure outputs independently, except in terms of input costs. No, we are not suggesting that the only growth enhancing technologies are innovations that increase the efficiency of primary conversion. There are also those that increase the supply of primary exergy. And in fact, the record since 1975 suggests otherwise. As Eq. (1) indicates, we view the economy as a set of linked materials-processing and value added (and information added) stages, forming a sequence. Eqs. (2) and (12) refer to a simplified situation, with only one intermediate product, namely useful work, U. The surprise is that this simplification proves to be such a good approximation to the complex reality and this despite quite considerable dynamic and structural changes to both economies reflected in increased exergy consumption as resource prices decline and/or faster efficiency improvements driven by scarcity and concomitant cost increases. We note that for much of the century resource prices were on a long-term down escalator, while labor prices were on a corresponding up escalator. For this reason, resource-intensive manufacturing businesses invested their capital with the specific objective of reducing labor requirements. They did this by investing heavily in exergy-intensive machines and equipment, and of course the feedback cycle (Fig. 1b) operated to keep the costs of primary exergy services (useful work) declining. From the early 70s to the late 80s this feedback cycle went partially into reverse. For the first time, resource prices rose sharply and there were significant efforts to reduce consumption of resources per se. Since the opportunities for short-term increases in primary exergy conversion efficiency were quite limited by that time, attention switched to finding cheap ways to decrease the consumption of electric power, and automotive fuels. Opportunities to save energy at low cost, or even at a profit, by improved ‘housekeeping’ were and still are widely available. Old and new buildings were better insulated, double and triple windows were installed, incandescent lights were replaced by compact fluorescent lights (and more recently LCDs) in many homes, refrigerators and air-conditioners were significantly improved partly by the use of better insulation and the so-called CAFE standards adopted by the US Congress, forced auto companies to double fleet average fuel economy over ten years (mainly by cutting the size and weight of new vehicles). These savings can be interpreted as increasing secondary efficiency, in the sense of Eq. (1). It can be expected that future gains in productivity will increasingly be achieved by improving secondary and (in due course) tertiary efficiency. Tertiary efficiency can be thought of as the efficiency with which secondary work produces finished goods and services. In conclusion, we would like to emphasize a crucial point once again. The neoclassical paradigm does not allow for ‘real’ material flows. Production and consumption are abstractions, linked only by money flows, payments for labor, payments for products and services, savings and investment. Resources are also abstractions. These abstract flows are governed only by equilibrium-seeking market forces (the ‘invisible hand’). The laws of physics play no role. Technological progress is exogenous, like ‘manna’ from heaven. Indeed, in the neoclassical paradigm long-term economic growth is simply assumed. It follows from this assumption that our grandchildren will be a lot richer than we are, whatever we do or do not do about global environmental problems such as climate warming (or ‘climate chaos’). Under these (supposed) circumstances, the obvious policy is to continue business-as-usual, in the belief that it is optimal to go on doing the things that made us rich in the first place. On the other hand, we treat the economy as a materials processing system, albeit governed by the laws of supply and demand as well as the laws of thermodynamics. The system consists of processing stages, starting with extraction, conversion, production of finished goods and services, final consumption and disposal of wastes. A description of the system includes materials and energy flows and gradients as well as money flows and price gradients. In this paradigm waste flows are inherent to the economic system. Moreover, the damages from waste flows to the environment can both reduce human welfare directly and increase the cost of finding resources, extracting, processing and disposing of waste materials. In this paradigm future human welfare, and perhaps even survival, depends upon adopting proactive policies and strategies to seek and, if necessary, subsidize more benign alternatives to the business-as-usual path on which we currently find ourselves.