Hot new directions for quasi-Monte Carlo research in step with applications

This article provides an overview of some interfaces between the theory of quasi-Monte Carlo (QMC) methods and applications. We summarize three QMC theoretical settings: first order QMC methods in the unit cube $[0,1]^s$ and in $\mathbb{R}^s$, and higher order QMC methods in the unit cube. One important feature is that their error bounds can be independent of the dimension $s$ under appropriate conditions on the function spaces. Another important feature is that good parameters for these QMC methods can be obtained by fast efficient algorithms even when $s$ is large. We outline three different applications and explain how they can tap into the different QMC theory. We also discuss three cost saving strategies that can be combined with QMC in these applications. Many of these recent QMC theory and methods are developed not in isolation, but in close connection with applications

The impact of metropolitan structure on commute behavior in the Netherlands: a multilevel approach

The effect of decentralization of land uses on travel behavior remains an unresolved issue in the academic literature. Some US researchers argue that a tendency towards polycentrism is associated with decreasing commute times and distances. Others have, however, suggested and shown the opposite commute times and distances tend to be longer in polycentric than in monocentric urban areas. Using this controversy as a starting point, we analyse how monocentric and polycentric urban structures affect commuting in the Netherlands with data from the 1998 National Travel Survey. Four kinds of urban systems are distinguished: one monocentric and three polycentric systems. In contrast to most previous work, we use multilevel regression analysis to take adequate account of the effects of individual and household attributes. The results indicate that urban structure influences most dimensions of commuting considered here. Yet, individual and household level variables are more important determinants than characteristics of the residential and workplace environment. Gender, household type and their interaction effects remain important determinants of commute behavior in the Netherlands; particularly women in two-earner households commute less than average. Education and income are both positively related to the amount of commuting. Further, the effects of mono- and polycentrism on commuting are more complicated than the literature makes us believe. When individual and household level factors are taken account of, polycentrism does not always result in more efficient commute patterns than monocentric urban structures: in most polycentric urban areas commute distances and times are longer than in monocentric ones. Only when polycentric regions consist of several relatively independent and self-contained development nodes are commute distances shorter than elsewhere. Commute times are in that case comparable to those in monocentric urban areas. The impact of urban structure disappears when commute time is related to the time spent on work activities; the ratio between commute time and work duration is not much affected by the type of urban system in which workers reside. The fact that commute times and distances are not lower in polycentric urban areas may be attributed to the specific situation in the Netherlands: strong spatial planning policies may have obstructed the relocation of employment and housing in close proximity of each other. However, the longer commute in most policentric regions may also indicate that workers and their households not always behave as urban economic theory predicts. In any case, the results show that it is necessary to distinguish several types of polycentric systems instead of merely using a dichotomy of monocentric and polycentric in the analysis of commuting.

Multilevel Analysis of Trachomatous Trichiasis and Corneal Opacity in Nigeria : The Role of Environmental and Climatic Risk Factors on the Distribution of Disease.

Funding: Jennifer L Smith was supported by the International Trachoma Initiative through a grant from the Bill and Melinda Gates Foundation. Anthony Solomon is a Wellcome Trust Intermediate Clinical Fellow (098521). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

How to Solve the Price Puzzle? A Meta-Analysis

The short-run increase in prices following an unexpected tightening of monetary policy represents a frequently reported puzzle. Yet the puzzle is easy to explain away when all published models are quantitatively reviewed. We collect and examine about 1,000 point estimates of impulse responses from 70 articles using vector autoregressive models to study monetary transmission in various countries. We find some evidence of publication selection against the price puzzle in the literature, but our results also suggest that the reported puzzle is mostly caused by model misspecifications. Finally, the long-run response of prices to monetary policy shocks depends on the characteristics of the economy.Monetary policy transmission; Price puzzle; Meta-analysis; Publication selection bias