Information, the Dual Economy, and Development

We examine the interactions between different institutional arrangements in a general equilibrium model of a modernizing economy. There is a modern sector, where productivity is high but information asymmetries are large, and a traditional sector where productivity is low but information asymmetries are low. Consequently, agency costs in the modern sector make consumption lending difficult, while such loans are readily obtainable in the traditional sector. The resulting trade-off between credit availability and productivity implies that not everyone will move to the modern sector. In fact, the laissex-fair level of modernization may fail to maximize net social surplus. This situation may also hold in the long run: in a dynamic version of the model, a "trickle-down" effect links the process of modernization with reduction in modern sector agency costs. This effect may be too weak and the economy may get stuck in a trap and never fully modernize. The two-sector structure also yields a natural testing ground for the Kuznets inverted-U hypothesis: we show that even within the "sectoral shifting" class of models, this phenomenon is not robust to small changes in model specification

Migration, Integration, and Development

We re-examine the Lewis undermigration by studying a two-sector model in which there is a trade-off between higher productivity in the modern sector and better information in the traditional sector. The consequent presence of well-functioning local insurance markets in the traditional sector and their absence in the modern sector leads to the possibility of inefficient undermigration: total social surplus would be increased if migration were larger than its laissez-faire level; whether this occurs depends in part on the distribution of wealth. In a dynamic version of the model, modernization of the economy may be too slow, and it is possible that the economy gets stuck in an undermigration trap (never fully modernizes). The migratory dynamics also lead to well-defined dynamic relations between average income and inequality. We find that although the Kuznets inverted-U curve may arise, it is equally likely that the relation of inequality and income follows other patterns, including an upright U

Information, the Dual Economy, and Development

We examine the interactions between different institutional arrangements in a general equilibrium model of a modernizing economy. There is a modern sector, where productivity is high but information asymmetries are large, and a traditional sector where productivity is low but information asymmetries are low. Consequently, agency costs in the modern sector make consumption lending difficult, while such loans are readily obtainable in the traditional sector. The resulting trade-off between credit availability and productivity implies that not everyone will move to the modern sector. In fact, the laissex-fair level of modernization may fail to maximize net social surplus. This situation may also hold in the long run: in a dynamic version of the model, a "trickle-down" effect links the process of modernization with reduction in modern sector agency costs. This effect may be too weak and the economy may get stuck in a trap and never fully modernize. The two-sector structure also yields a natural testing ground for the Kuznets inverted-U hypothesis: we show that even within the "sectoral shifting" class of models, this phenomenon is not robust to small changes in model specification

On the choice of calibration metrics for “high-flow” estimation using hydrologic models

Calibration is an essential step for improving the accuracy of simulations generated using hydrologic models. A key modeling decision is selecting the performance metric to be optimized It has been common to use squared error performance metrics, or normalized variants such as Nash-Sutcliffe efficiency (NSE), based on the idea that their squared-error nature will emphasize the estimates of high flows. However, we conclude that NSE-based model calibrations actually result in poor reproduction of high-flow events, such as the annual peak flows that are used for flood frequency estimation. Using three different types of performance metrics, we calibrate two hydrological models at a daily step, the Variable Infiltration Capacity (VIC) model and the mesoscale Hydrologic Model (mHM), and evaluate their ability to simulate high-flow events for 492 basins throughout the contiguous United States. The metrics investigated are (1) NSE, (2) Kling-Gupta efficiency (KGE) and its variants, and (3) annual peak flow bias (APFB), where the latter is an application-specific metric that focuses on annual peak flows. As expected, the APFB metric produces the best annual peak flow estimates; however, performance on other high-flow-related metrics is poor. In contrast, the use of NSE results in annual peak flow estimates that are more than 20 % worse, primarily due to the tendency of NSE to underestimate observed flow variability. On the other hand, the use of KGE results in annual peak flow estimates that are better than from NSE, owing to improved flow time series metrics (mean and variance), with only a slight degradation in performance with respect to other related metrics, particularly when a non-standard weighting of the components of KGE is used. Stochastically generated ensemble simulations based on model residuals show the ability to improve the high-flow metrics, regardless of the deterministic performances. However, we emphasize that improving the fidelity of streamflow dynamics from deterministically calibrated models is still important, as it may improve high-flow metrics (for the right reasons). Overall, this work highlights the need for a deeper understanding of performance metric behavior and design in relation to the desired goals of model calibration.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Occupational Choice and the Process of Development

This paper models economic development as a process of institutional transformation by focusing on the interplay between agents' occupational decisions and the distribution of wealth. Because of capital market imperfections, poor agents choose working for a wage over self-employment, and wealthy agents become entrepreneurs who monitor workers. However, only with sufficient in equality will there be employment contracts; otherwise, depending on average wealth, there is either stagnation or self-employment. Thus, in a static context, the occupational structure depends on distribution. Since the distribution of wealth is itself endogenous, however, we demonstrate the robustness of this result by extending the model dynamically and studying examples in which initial wealth distributions have long run effects. In one case the economy develops into prosperity or stagnation, depending on the initial distribution; in the other example, it develops either widespread cottage industry (self-employment) or factory production (employment contracts).

Galaxy Peculiar Velocities From Large-Scale Supernova Surveys as a Dark Energy Probe

Upcoming imaging surveys such as the Large Synoptic Survey Telescope will repeatedly scan large areas of sky and have the potential to yield million-supernova catalogs. Type Ia supernovae are excellent standard candles and will provide distance measures that suffice to detect mean pairwise velocities of their host galaxies. We show that when combining these distance measures with photometric redshifts for either the supernovae or their host galaxies, the mean pairwise velocities of the host galaxies will provide a dark energy probe which is competitive with other widely discussed methods. Adding information from this test to type Ia supernova photometric luminosity distances from the same experiment, plus the cosmic microwave background power spectrum from the Planck satellite, improves the Dark Energy Task Force Figure of Merit by a factor of 1.8. Pairwise velocity measurements require no additional observational effort beyond that required to perform the traditional supernova luminosity distance test, but may provide complementary constraints on dark energy parameters and the nature of gravity. Incorporating additional spectroscopic redshift follow-up observations could provide important dark energy constraints from pairwise velocities alone. Mean pairwise velocities are much less sensitive to systematic redshift errors than the luminosity distance test or weak lensing techniques, and also are only mildly affected by systematic evolution of supernova luminosity.Comment: 18 pages; 4 figures; 4 tables; replaced to match the accepted versio

A quantitative analysis of measures of quality in science

Condensing the work of any academic scientist into a one-dimensional measure of scientific quality is a difficult problem. Here, we employ Bayesian statistics to analyze several different measures of quality. Specifically, we determine each measure's ability to discriminate between scientific authors. Using scaling arguments, we demonstrate that the best of these measures require approximately 50 papers to draw conclusions regarding long term scientific performance with usefully small statistical uncertainties. Further, the approach described here permits the value-free (i.e., statistical) comparison of scientists working in distinct areas of science.Comment: 11 pages, 8 figures, 4 table

Recruitment of ethnic minority patients to a cardiac rehabilitation trial: The Birmingham Rehabilitation Uptake Maximisation (BRUM) study [ISRCTN72884263]

Background: Concerns have been raised about low participation rates of people from minority ethnic groups in clinical trials. However, the evidence is unclear as many studies do not report the ethnicity of participants and there is insufficient information about the reasons for ineligibility by ethnic group. Where there are data, there remains the key question as to whether ethnic minorities more likely to be ineligible (e.g. due to language) or decline to participate. We have addressed these questions in relation to the Birmingham Rehabilitation Uptake Maximisation (BRUM) study, a randomized controlled trial (RCT) comparing a home-based with a hospital-based cardiac rehabilitation programme in a multi-ethnic population in the UK. Methods: Analysis of the ethnicity, age and sex of presenting and recruited subjects for a trial of cardiac rehabilitation in the West-Midlands, UK. Participants: 1997 patients presenting post-myocardial infarction, percutaneous transluminal coronary angioplasty or coronary artery bypass graft surgery. Data collected: exclusion rates, reasons for exclusion and reasons for declining to participate in the trial by ethnic group. Results: Significantly more patients of South Asian ethnicity were excluded (52% of 'South Asian' v 36% 'White European' and 36% 'Other', p < 0.001). This difference in eligibility was primarily due to exclusion on the basis of language (i.e. the inability to speak English or Punjabi). Of those eligible, similar proportions were recruited from the different ethnic groups (white, South Asian and other). There was a marked difference in eligibility between people of Indian, Pakistani or Bangladeshi origin

Large N Phases, Gravitational Instantons and the Nuts and Bolts of AdS Holography

Recent results in the literature concerning holography indicate that the thermodynamics of quantum gravity (at least with a negative cosmological constant) can be modeled by the large N thermodynamics of quantum field theory. We emphasize that this suggests a completely unitary evolution of processes in quantum gravity, including black hole formation and decay; and even more extreme examples involving topology change. As concrete examples which show that this correspondence holds even when the space-time is only locally asymptotically AdS, we compute the thermodynamical phase structure of the AdS-Taub-NUT and AdS-Taub-Bolt spacetimes, and compare them to a 2+1 dimensional conformal field theory (at large N) compactified on a squashed three sphere, and on the twisted plane.Comment: 20 pages, three figures. (uses harvmac.tex and epsf.tex

Dementia and Imagination: a mixed-methods protocol for arts and science research

ABSTRACT Introduction: Dementia and Imagination is a multidisciplinary research collaboration bringing together arts and science to address current evidence limitations around the benefits of visual art activities in dementia care. The research questions ask: Can art improve quality of life and well-being? If it does make a difference, how does it do this-and why? Does it have wider social and community benefits? Methods and analysis: This mixed-methods study recruits participants from residential care homes, National Health Service (NHS) wards and communities in England and Wales. A visual art intervention is developed and delivered as 1×2-hour weekly group session for 3 months in care and community settings to N=100 people living with dementia. Quantitative and qualitative data are collected at 3 time points to examine the impact on their quality of life, and the perceptions of those who care for them (N=100 family and professional carers). Repeated-measures systematic observations of well-being are obtained during the intervention (intervention vs control condition). The health economics component conducts a social return on investment evaluation of the intervention. Qualitative data are collected at 3 time points (n=35 carers/staff and n=35 people living with dementia) to explore changes in social connectedness. Self-reported outcomes of the intervention delivery are obtained (n=100). Focus groups with intervention participants (n=40) explore perceptions of impact. Social network analysis of quantitative and qualitative data from arts and healthcare professionals (N=100) examines changes in perceptions and practice. Ethics and dissemination: The study is approved by North Wales Research Ethics Committee-West. A range of activities will share the research findings, including international and national academic conferences, quarterly newsletters and the project website. Public engagement projects will target a broad range of stakeholders. Policy and practice summaries will be developed. The visual art intervention protocol will be developed as a freely available practitioners guide