Generalized Direct Sampling for Hierarchical Bayesian Models

We develop a new method to sample from posterior distributions in hierarchical models without using Markov chain Monte Carlo. This method, which is a variant of importance sampling ideas, is generally applicable to high-dimensional models involving large data sets. Samples are independent, so they can be collected in parallel, and we do not need to be concerned with issues like chain convergence and autocorrelation. Additionally, the method can be used to compute marginal likelihoods

Scalable Rejection Sampling for Bayesian Hierarchical Models

Bayesian hierarchical modeling is a popular approach to capturing unobserved heterogeneity across individual units. However, standard estimation methods such as Markov chain Monte Carlo (MCMC) can be impracticable for modeling outcomes from a large number of units. We develop a new method to sample from posterior distributions of Bayesian models, without using MCMC. Samples are independent, so they can be collected in parallel, and we do not need to be concerned with issues like chain convergence and autocorrelation. The algorithm is scalable under the weak assumption that individual units are conditionally independent, making it applicable for large datasets. It can also be used to compute marginal likelihoods

European Industrial Policy: The Airbus Case

industrial policy; airframe industry; calibration

Characterising submonolayer deposition via visibility graphs

We use visibility graphs as a tool to analyse the results of kinetic Monte Carlo (kMC) simulations of submonolayer deposition in a one-dimensional point island model. We introduce an efficient algorithm for the computation of the visibility graph resulting from a kMC simulation and show that from the properties of the visibility graph one can determine the critical island size, thus demonstrating that the visibility graph approach, which implicitly combines size and spatial data, can provide insights into island nucleation and growth processes

Bank Performance in Transition Economies

This paper examines the performance of 515 banks in 16 transition economies for the years 1994 – 99 based on their public financial accounts. We first examine lending behaviour and probability distribution of bank profitability to determine whether these banks exhibit behaviour and performance associated with excessive risk-taking. While we do not find evidence of excessive risk taking on average where there is significant progress in banking and related enterprise reforms, there may be a minority of poorly capitalised banks that do take excessive risks, particularly where progress in reform is less advanced. The paper then estimates cost and revenue functions based on a model of banks as multi-product firms. The results indicate that banks' performance differs significantly depending on the reform environment, as well as the competitive conditions, in which they operate. Banks with high market shares have higher costs and achieve lower margins on their loan and deposit activities. Where there has been significant progress in banking and related enterprise reforms, banks are making comfortable margins on loans and appear to be offering competitive margins on deposits, though they are still achieving overall negative returns on equity. By contrast, when substantial reforms have not been undertaken, banks have been sustaining high negative returns on loans, largely at the expense of depositors; in effect they have been able to appropriate much of the tax that inflation levies on nominal deposits, and have been using this revenue to prop up their weak loan portfolios. Overall interest margins are declining over time but are substantially higher in low reform environments. The results indicate that an appropriate policy and regulatory framework may be a necessary condition for significant progress to be made.http://deepblue.lib.umich.edu/bitstream/2027.42/39890/3/wp505.pd

Bank Performance in Transition Economies

This paper examines the performance of 515 banks in 16 transition economies for the years 1994 – 99 based on their public financial accounts. We first examine lending behaviour and probability distribution of bank profitability to determine whether these banks exhibit behaviour and performance associated with excessive risk-taking. While we do not find evidence of excessive risk taking on average where there is significant progress in banking and related enterprise reforms, there may be a minority of poorly capitalised banks that do take excessive risks, particularly where progress in reform is less advanced. The paper then estimates cost and revenue functions based on a model of banks as multi-product firms. The results indicate that banks' performance differs significantly depending on the reform environment, as well as the competitive conditions, in which they operate. Banks with high market shares have higher costs and achieve lower margins on their loan and deposit activities. Where there has been significant progress in banking and related enterprise reforms, banks are making comfortable margins on loans and appear to be offering competitive margins on deposits, though they are still achieving overall negative returns on equity. By contrast, when substantial reforms have not been undertaken, banks have been sustaining high negative returns on loans, largely at the expense of depositors; in effect they have been able to appropriate much of the tax that inflation levies on nominal deposits, and have been using this revenue to prop up their weak loan portfolios. Overall interest margins are declining over time but are substantially higher in low reform environments. The results indicate that an appropriate policy and regulatory framework may be a necessary condition for significant progress to be made.banking, cost functions, revenue functions, transition

Physicians' Practice of Dispensing Medicines: A Qualitative Study

Objectives: The physical act of giving medication to patients to administer away from a health care setting, dispensing, is normally performed by pharmacists. Dispensing of medication by physicians is a neglected patient safety issue, and having observed considerable variation in practice, the lead author sought to explore this issue further. A literature review yielded zero articles pertaining to this, so an exploratory study was commenced. The qualitative arm, relating to junior physicians' experience of, and training in, dispensing, is reported here. Methods: Focus groups were conducted to explore the beliefs, ideas, and experiences of physicians-in-training pertaining to dispensing of medication. These were recorded and transcribed. The transcriptions were thematically analyzed using the grounded theory. Results: The emergency department was the most common site of dispensing. No formal training in dispensing had been received. Informal training was variable in content and utility. The physicians felt that dispensing was part of their role. Conclusions: Despite being expected to dispense, and the patient safety issues involved in giving drugs to patients to use at home, physicians do not feel that they have been trained to undertake this task. These findings from 1 hospital raise questions about thewider quality and safety of this practic

Entropic Inflation

One of the major pillars of modern cosmology theory is a period of accelerating expansion in the early universe. This accelerating expansion, or inflation, must be sustained for at least 30 e--foldings. One mechanism used to drive the acceleration is the addition of a new energy field, called the Inflaton; often this is a scalar field. We propose an alternative mechanism which, like our approach to explain the late-time accelerating universe, uses the entropy and temperature intrinsic to information holographically stored on a surface enclosing the observed space. The acceleration is due in both cases to an emergent entropic force, naturally arising from the information storage on the horizon.Comment: 12 pages; version to appear in IJMP