An analysis of RSQE forecasts: 1971–1992

The purpose of this paper is to evaluate the accuracy of ex ante econometric model forecasts of four key macroeconomic variables: real GNP growth, the rate of price inflation measured by the GNP deflator, the civilian unemployment rate, and the Treasury Bill rate. Annual forecasts produced by the Research Seminar in Quantitative Economics (RSQE) based on the Michigan Quarterly Econometric Model of the U.S. Economy are compared with quasi ex ante forecasts from a four-variable vector autoregressive (VAR) model. Statistical tests of the equality of forecast error variances as well as univariate and multivariate forecast encompassing-type tests are conducted. The forecast error variance comparisons indicate that for three of the four variables the RSQE forecasts are more accurate than the VAR forecasts and for one of the variables (real GNP growth) only slightly less accurate. The forecast encompassing-type tests indicate that the RSQE forecasts contain information not contained in the VAR forecasts and, conversely, that VAR forecasts contain information not included in the RSQE forecasts. The scope for improving RSQE forecasts by combining them with VAR forecasts is rather limited, however.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43925/1/11293_2006_Article_BF02299030.pd

Safe Crossover of Neural Networks Through Neuron Alignment

One of the main and largely unexplored challenges in evolving the weights of neural networks using genetic algorithms is to find a sensible crossover operation between parent networks. Indeed, naive crossover leads to functionally damaged offspring that do not retain information from the parents. This is because neural networks are invariant to permutations of neurons, giving rise to multiple ways of representing the same solution. This is often referred to as the competing conventions problem. In this paper, we propose a two-step safe crossover(SC) operator. First, the neurons of the parents are functionally aligned by computing how well they correlate, and only then are the parents recombined. We compare two ways of measuring relationships between neurons: Pairwise Correlation (PwC) and Canonical Correlation Analysis (CCA). We test our safe crossover operators (SC-PwC and SC-CCA) on MNIST and CIFAR-10 by performing arithmetic crossover on the weights of feed-forward neural network pairs. We show that it effectively transmits information from parents to offspring and significantly improves upon naive crossover. Our method is computationally fast,can serve as a way to explore the fitness landscape more efficiently and makes safe crossover a potentially promising operator in future neuroevolution research and applications

Measurement in Economics and Social Science

The paper discusses measurement, primarily in economics, from both analytical and historical perspectives. The historical section traces the commitment to ordinalism on the part of economic theorists from the doctrinal disputes between classical economics and marginalism, through the struggle of orthodox economics against socialism down to the cold-war alliance between mathematical social science and anti-communist ideology. In economics the commitment to ordinalism led to the separation of theory from the quantitative measures that are computed in practice: price and quantity indexes, consumer surplus and real national product. The commitment to ordinality entered political science, via Arrow’s ‘impossibility theorem’, effectively merging it with economics, and ensuring its sterility. How can a field that has as its central result the impossibility of democracy contribute to the design of democratic institutions? The analytical part of the paper deals with the quantitative measures mentioned above. I begin with the conceptual clarification that what these measures try to achieve is a restoration of the money metric that is lost when prices are variable. I conclude that there is only one measure that can be embedded in a satisfactory economic theory, free from unreasonable restrictions. It is the Törnqvist index as an approximation to its theoretical counterpart the Divisia index. The statistical agencies have at various times produced different measures for real national product and its components, as well as related concepts. I argue that all of these are flawed and that a single deflator should be used for the aggregate and the components. Ideally this should be a chained Törnqvist price index defined on aggregate consumption. The social sciences are split. The economic approach is abstract, focused on the assumption of rational and informed behavior, and tends to the political right. The sociological approach is empirical, stresses the non-rational aspects of human behavior and tends to the political left. I argue that the split is due to the fact that the empirical and theoretical traditions were never joined in the social sciences as they were in the natural sciences. I also argue that measurement can potentially help in healing this split

Generalized Canonical Regression

This paper introduces a generalized approach to canonical regression, in which a set of jointly dependent variables enters the left-hand side of the equation as a linear combination, formally like the linear combination of regressors in the right-hand side of the equation. Natural applications occur when the dependent variable is the sum of components that may optimally receive unequal weights or in time series models in which the appropriate timing of the dependent variable is not known a priori. The paper derives a quasi-maximum likelihood estimator as well as its asymptotic distribution and provides illustrative applications

Internet Retailing as a Marketing Strategy

We analyze the incentives for incumbent bricks-and-mortar firms and new entrants to start an online retail channel in a differentiated goods market. To this end we set up a two-stage model where firms first decide whether or not to build the infrastructure necessary to start an online retail channel and then compete in prices using the channels they have opened up. Consumers trade-off the convenience of online shopping and the ease to compare prices, with online uncertainties. Without a threat of entry by a third pure online player we find that for most parameter constellations firms' dominant strategy is not to open an online retail channel as this cannibalizes too much on their conventional sales. As the cannibalization effect is not present for a pure Internet player, we show that these firms will start online retail channels under a much wider range of parameter constellations. The threat of entry may force incumbent bricks-and-mortar firms to deter entry by starting up an Internet retail channel themselves. We also show that a low cost of building up an online retail channel or online shopping conveniences may not be to the benefit of online shopping as the strategic interaction between firms may be such that no online retail channel is built when the circumstances seem to be more favourable

Integrated Economic and Climate Modeling

This survey examines the history and current practice in integrated assessment models (IAMs) of the economics of climate change. It begins with a review of the emerging problem of climate change. The next section provides a brief sketch of the rise of IAMs in the 1970s and beyond. The subsequent section is an extended exposition of one IAM, the DICE/RICE family of models. The purpose of this description is to provide readers an example of how such a model is developed and what the major components are. The final section discusses major important open questions that continue to occupy IAM modelers. These involve issues such as the discount rate, uncertainty, the social cost of carbon, the potential for catastrophic climate change, algorithms, and fat-tailed distributions. These issues are ones that pose both deep intellectual challenges as well as important policy implications for climate change and climate-change policy

COALMOD-World: A Model to Assess International Coal Markets Until 2030

Coal continues to be an important fuel in many countries' energy mix and, despite the climate change concerns, it is likely to maintain this position for the next decades. In this paper a numerical model is developed to investigate the evolution of the international market for steam coal, the coal type used for electricity generation. The main focus is on future trade ows and investments in production and transport infrastructure until 2030. COALMOD-World is an equilibrium model, formulated in the complementarity format. It includes all major steam coal exporting and importing countries and represents the international trade as one globalized market. Some suppliers of coal are at the same time major consumers, such as the USA and China. Therefore, domestic markets are also included in the model to analyze their interaction with the international market. Because of the different qualities of steam coal, we include different heating values depending on the origin of the coal. At the same time we observe the mass-specific constraints on production, transport and export capacity. The time horizon of our analysis is until 2030, in 5-year steps. Production costs change endogenously over time. Moreover, endogenous investments are included based on a net present value optimization approach and and the shadow prices of capacities constraints. Investments can be carried out in production, inland freight capacities (rail in most countries), and export terminals. The paper finishes with an application of the model to a base case scenario and suggestions for alternative scenarios