Channeling Fisher: randomization tests and the statistical insignificance of seemingly significant experimental results

I follow R. A. Fisher's The Design of Experiments (1935), using randomization statistical inference to test the null hypothesis of no treatment effects in a comprehensive sample of 53 experimental papers drawn from the journals of the American Economic Association. In the average paper, randomization tests of the significance of individual treatment effects find 13% to 22% fewer significant results than are found using authors’ methods. In joint tests of multiple treatment effects appearing together in tables, randomization tests yield 33% to 49% fewer statistically significant results than conventional tests. Bootstrap and jackknife methods support and confirm the randomization results

Demographic Fluctuations, Generational Welfare and Intergenerational Transfers

This paper extends the Ramsey model's normative analysis to issues of generational welfare and intergenerational transfers. A planner, who maximizes the discounted welfare of an endless stream of generations, is intrinsically biased against larger cohorts, which are more costly to provide utility. Imperfect production substitutability produces a market bias against baby booms as well, lowering their lifetime income. The market bias, however, tends to be greater than that of the planner, who provides the baby boom cohort with more favourable lifetime transfers. Intuitively, the baby boom benefits from temporarily reduced elderly dependency, allowing greater lifetime consumption relative to lifetime income. Declining population growth leads to rising elderly dependency, which the planner supports with increasing intergenerational transfers. Secularly rising social security taxes, and declining lifetime returns, with a baby boom cohort receiving more favourable treatment than their heavily burdened successors, are consistent with the wishes of a social planner in an environment with declining population growth.

The Razor's Edge: Distortions and Incremental Reform in the People's Republic of China

In a partially reformed economy, distortions beget distortions. Segments of the economy which are freed from centralized control respond to the rent seeking opportunities implicit in the remaining distortions of the economy. The battle to capture, and then protect, these rents leads to the creation of new distortions, even as the reform process tries to move forward. In this paper I illustrate this idea with a study of the People's Republic of China. Under the plan, prices were skewed so as to concentrate profits, and hence revenue, in industry. As control over factor allocations was loosened, local governments throughout the economy sought to capture these rents by developing high margin industries. Continued reform, and growing interregional competition between duplicative industries, threatened the profitability of these industrial structures, leading local governments to impose a variety of interregional barriers to trade. Thus, the reform process led to the fragmentation of the domestic market and the distortion of regional production away from patterns of comparative advantage.

Invention and Bounded Learning by Doing

This paper presents a model of the interaction between invention and learning by doing. Learning depends upon invention in that learning by doing is viewed as the serendipitous exploration of the finite productive potential of invented technologies. At the same time, the profitability of costly invention is dependent upon learning in that costs of production depend upon the society's aggregate historical learning experience. The resulting model is a true hybrid. With small markets, the profitability of invention is low, and hence the rate of invention becomes the constraining factor in growth. With large markets, invention is very profitable and tends to pull ahead of the society's learning experience. The consequent growing gap between the technological frontier and the society's industrial maturity squeezes returns, leading to an equilibrium in which the rate of invention (and growth) is paced by the society's rate of learning.

Learning by Doing and the Dynamic Effects of International Trade

Using an endogenous growth model in which learning by doing, although bounded in each good, exhibits spillovers across goods, this paper investigates the dynamic effects of international trade. Examining an LDC and a DC, the latter distinguished by a higher initial level of knowledge, under autarky and free trade, I find that under free trade the LDC (DC) experiences rates of technical progress and GOP growth less than or equal (greater than or equal) to those enjoyed under autarky. Unless the LDC's population is several orders of magnitude greater than that of the DC and the initial technical gap between the two economies is not large, the LDC will be unable to catch up with its trading partner. Hence, in terms of technical progress and growth, the LDC experiences dynamic losses from trade, whilst the DC experiences dynamic gains. However, since technical progress abroad can improve welfare at home, LDC consumers may enjoy - higher intertemporal utility along the free trade path. In the case of DC consumers, as long as their economy is not overtaken by the LDC they will enjoy both more rapid technical progress and the traditional static gains from trade, and hence experience an unambiguous improvement in intertemporal welfare.

Substitution and Complementarity in Endogenous Innovation

The influence of Schumpeter's notion of "creative destruction" may have led to an overemphasis on substitution between technologies in recent models of endogenous innovation. Historical examples of technological change suggest that new technologies may just as frequently complement older technologies, creating, rather than destroying, rents. Acknowledgement of the potential for both substitution and complementarity amongst inventions allows for a much richer characterization of the growth process, creating the possibility of threshold effects and multiple equilibria, and bringing to the forefront the important role played by the expectations of inventive entrepreneurs.

Alternative Estimates of Productivity Growth in the NICs: A Comment on the Findings of Chang-Tai Hsieh

Dual estimates of productivity growth by Chang-Tai Hsieh have raised questions about the accuracy of the East Asian national accounts, suggesting that productivity growth in the NICs, particularly Singapore, may have been substantially higher than previously estimated. This paper shows that once one corrects for computational and methodological errors, dual estimates, using Hsieh's own data, are not that far removed from the results implied by primal sources. Further, Hsieh's criticisms of the accuracy of the national accounts capital formation figures are shown to be invalid. Finally, other data exist which support the picture of declining real rentals painted by the national accounts capital formation figures.

Growth Without Scale Effects

An increase in the size (scale) of an economy increases the total quantity of rents that can be captured by successful innovators which, in equilibrium, should lead to a rise in innovative activity. Conventional wisdom and the theoretical predictions of models of endogenous innovation suggest that this increased research effort should lead to more rapid growth. As noted by Jones [1993], this prediction is at odds with the postwar experience of the OECD, where the growth of the market has indeed led to an increased R&D effort which, however, has been translated into stagnant or declining growth rates. Drawing upon the remarkable insights of the museum curator S.C. Gilfillan [1935], this paper modifies models of endogenous innovation to allow for the possibility that a rise in the profitability of innovative activity could lead to an increased variety of differentiated solutions to similar problems. An increased variety of technologies (e.g. an increase in the number and types of contraceptives) will increase the level of utility of the average consumer. If, however, continued improvement of this increased variety of technologies requires increased research input, a rise in the scale of the market could raise the equilibrium quantity of R&D, without increasing the economy's growth rate. Furthermore, increased product variety, brought about by increases in market size, might reduce the returns to improving product quality, paradoxically lowering an economy's growth rate while increasing the total resources devoted to R&D.

Paasche vs. Laspeyres: The Elasticity of Substitution and Bias in Measures of TFP Growth

In recent papers, Nelson and Pack (1995) , Rodrik (1997), and Hsieh (1997a) argue that standard measures of total factor productivity growth in countries where the capital-labour ratio has risen rapidly, e.g. the East Asian NICS, will understate true productivity growth if the elasticity of substitution is less than one and there is labour augmenting technical change. This note shows that this argument increases a Paasche measure of productivity, at the expense of lowering a Laspeyres estimate. The conditions under which total factor productivity growth is consistently underestimated are clarified.