Forecasting Issues: Ideas of Decomposition and Combination

Combination techniques and decomposition procedures have been applied to time series forecasting to enhance prediction accuracy and to facilitate the analysis of data respectively. However, the restrictive complexity of some combination techniques and the difficulties associated with the application of the decomposition results to the extrapolation of data, mainly due to the large variability involved in economic and financial time series, have limited their application and compromised their development. This paper is a re-examination of the benefits and limitations of decomposition and combination techniques in the area of forecasting, and a contribution to the field with a new forecasting methodology. The new methodology is based on the disaggregation of time series components through the STL decomposition procedure, the extrapolation of linear combinations of the disaggregated sub-series, and the reaggregation of the extrapolations to obtain estimation for the global series. With the application of the methodology to the data from the NN3 and M1 Competition series, the results suggest that it can outperform other competing statistical techniques. The power of the method lies in its ability to perform consistently well, irrespective of the characteristics, underlying structure and level of noise of the data.ARIMA models, combining forecasts, decomposition, error measures, evaluating forecasts, forecasting competitions, time series

Calendar Time Sampling of High Frequency Financial Asset Price and the Verdict on Jumps

In the current paper, we investigate the bias introduced through the calendar time sampling of the price process of financial assets. We analyze results from a Monte Carlo simulation which point to the conclusion that the multitude of jumps reported in the literature might be, to a large extent, an artifact of the bias introduced through the previous tick sampling scheme, used for the time homogenization the price series. We advocate the use of Akima cubic splines as an alternative to the popular previous tick method. Monte Carlo simulation results confirm the suitability of Akima cubic splines in high frequency applications and the advantages of these over other calendar time sampling schemes, such as the linear interpolation and the previous tick method. Empirical results from the FX market complement the analysis.Sampling schemes, previous tick method, quadratic variation, jumps, stochastic volatility,realized measures, high-frequency data

A Comprehensive Comparison of Alternative Tests for Jumps in Asset Prices

This paper presents a comprehensive comparison of nonparametric tests for jumps in the prices of financial assets. The relative performance of eight tests is examined in a Monte Carlo simulation covering scenarios of both finite and infinite activity jumps, and stochastic volatility models with continuous and discontinuous volatility sample paths. The main contribution of the paper is an investigation of the performance of the tests in the presence of various market microstructure effects, including microstructure noise, infrequent trading and deterministic diurnal volatility. The simulation results reveal important differences in terms of size and power of the tests across the different data generating processes. Zero intraday returns and microstructure frictions are shown to induce important distortions. An empirical application to prices from the forex market, stock market and futures market complements the analysis.Quadratic variation, jumps, stochastic volatility, realized measures,high-frequency data

Socio-economic differences in the job satisfaction of high-paid and low-paid workers in Greece

Using data from eight waves (1994-2001) of the European Community Household Panel (ECHP), this study examines whether significant differences exist in the perceived quality of high and low-paid jobs in Greece. After correcting for the potential selectivity problem that is prevalent in the study of the effect of low pay status on job satisfaction, evidence is presented that low wage workers are significantly less satisfied with their jobs compared to their higher-paid counterparts. Further analysis of the specific facets of jobs reveals that the lower average satisfaction of low-paid employees in Greece arises not only due to their lesser pay, but mainly because of the inferior type of work that they perform. Low-paid workers in Greece therefore seem to suffer from a double penalty, as their jobs are also of bad quality. In view of this segmentation, combined with the fact that Greece remains a low wage economy, it becomes evident that policies that centre on the quality of jobs are of equal importance to those that focus on the level of pay that they provide.job satisfaction, low-paid versus high-paid jobs, Greek labour market

Socioeconomic Evaluation and Ranking of Infrastructure Projects

For most of the last century, the role of private and public sectors in the infrastructure projects were clear. For instance, public authorities were generally in charge of financing and building new infrastructures. Over the last decade, that position has begun to change. Faced with pressure to reduce public sector debt and, at the same time, expand and improve public facilities, governments and public authorities have looked to private sector finance, and have invited private sector entities to enter into long-term contractual agreements which may take the form of construction or management of public sector infrastructure facilities by the private sector entity, or the provision of services (using infrastructure facilities) by the private sector entity to the community on behalf of a public sector body. This paper deals with the new issues raised by the public-private partnerships system or, more generally, by any system in which the new infrastructure is partially financed by its users. Is there, in this case, a new economic rationality of public authorities? Particularly, is there an optimal way to rank projects? This paper discusses the choice by the public authority of the most efficient investing programme in irrigation water infrastructures. More specifically, it studies the optimal ranking of project implementation when these projects are partially self-financed by their own revenues. In this case, the optimal investment programme must be defined under a constraint of annual subsidies. This paper demonstrates that the optimal ranking is not necessarily the ranking of decreasing socioeconomic internal rate of return. This counter-intuitive result can be demonstrated by a general approach. Analytical calculations are not useful in this discrete problem because each programme is an ordered subset of projects. Therefore, there is no continuous variation linking the various programmes and the usual tools of optimization, such as differential calculus, are useless. Thus, we adopt here a discrete optimization analysis based on standard techniques in the physics area, such as Monte Carlo sampling.

Why do so many students elect to study graphic design?

According to the latest stats from the Higher Education Statistics Agency (HESA), 182,085 students were studying creative arts and design in 2011/12 (www.hesa.ac.uk/content/ view/1897/239). Although graphic design students make up some of this number, it still leads to the question – why do so many students want to be educated in this subject – there can not possibly be an equal number of creative jobs to fill each year. Right? This article documents some of the student experiences on the Graphic Design course at Epsom and the opportunities on offer

Revisiting the anomalous rf field penetration into a warm plasma

Radio frequency waves do not penetrate into a plasma and are damped within it. The electric field of the wave and plasma current are concentrated near the plasma boundary in a skin layer. Electrons can transport the plasma current away from the skin layer due to their thermal motion. As a result, the width of the skin layer increases when electron temperature effects are taken into account. This phenomenon is called anomalous skin effect. The anomalous penetration of the rf electric field occurs not only for transversely propagating to the plasma boundary wave (inductively coupled plasmas) but also for the wave propagating along the plasma boundary (capacitively coupled plasmas). Such anomalous penetration of the rf field modifies the structure of the capacitive sheath. Recent advances in the nonlinear, nonlocal theory of the capacitive sheath are reported. It is shown that separating the electric field profile into exponential and non-exponential parts yields an efficient qualitative and quantitative description of the anomalous skin effect in both inductively and capacitively coupled plasma.Comment: 44 pages, invited paper at "Nonlocal, Collisionless Phenomena in Plasma" worksho

Advancing task involvement, intrinsic motivation and metacognitive regulation in physical education classes: the self-check style of teaching makes a difference

It was hypothesized that “self-check” style of teaching would be more preferable in terms of creating a mastery-oriented climate, and promoting adaptive achievement goals, intrinsic motivation and metacognitive activity in physical education classes. Two hundred seventy-nine (N = 269) 6-grade students were randomly divided into two groups that were taught four consecutive physical education lessons of the same content following either “practice” or “self-check” styles of teaching respectively. Students responded on questionnaires prior and after the intervention. Results revealed significant interactions between groups and measurements. Students in the “self-check” style group scored higher in scales measuring mastery-oriented climate, mastery goal, intrinsic motivation and metacognitive processes and lower in scales measuring performance-goals and performance-oriented motivational climate. These results underscore the importance of using styles of teaching that enhance opportunities for deep cognitive processing and promote mastery-goals and mastery-oriented climates

ROLE OF THE NEURONAL SPECIFIC TRANSCRIPTION COREGULATOR NPDC-1 IN RETINOID AND THYROID RECEPTOR SIGNALING IN HUMAN AND THE AXOLOTL AMBYSTOMA MEXICANUM

Section I: This section is an introduction to the field of nuclear receptors. A general overview of nuclear receptor-mediated transcriptional regulation is followed by a review of literature on retinoid and thyroid receptor-mediated signaling. Section II: An introduction to NPDC-1 (neural proliferation, differentiation, and control), its discovery and characterization with regards to developmental expression and cellular localization. In addition NPDC-1 has been found to associate with a number of cell cycle regulatory proteins. NPDC-1 is characterized as a regulator of nuclear receptor-mediated transcriptional regulation. NPDC-1 was also demonstrated to be regulated post-transcriptionally through the ubiquitin/proteosome degradation pathway. Section III: Axolotl NPDC-1 (aNPDC-1) was cloned from axolotl brain and analyzed for homology to NPDC-1 from higher vertebrates. The tissue distribution and developmental expression of axolotl NPDC-1 were also examined. Section IV: The axolotl homolog for RAR (aRAR) was isolated from axolotl brain. Axolotl NPDC-1 and aRAR were then examined in a series of assays for interactions. Axolotl NPDC-1 was found to repress transcription mediated by aRAR to a smaller extent than the repression observed in higher vertebrates. The DNA binding of aRAR-RXR was increased in the presence of aNPDC-1 and complex mobility was also observed. The domain of interaction between aNPDC-1, aRAR and hRXR was localized in the amino terminus of aNPDC-1. Axolotl NPDC-1 was also demonstrated to repress proliferation as measured by reduced [3H] thymidine incorporation. Section V: The axolotl homologs of TR and TR (aTR) genes were isolated and utilized in a series of experiments to demonstrate an interaction between aTRs and aNPDC-1. As observed for RE, aNPDC-1 increases the binding of aTR-RXR heterodimer to xDR4, but no change in the mobility of the complex was observed. Interaction between aNPDC-1, aTR and aTR was localized to the amino terminus of aNPDC-1. In contrast to previous observations for other nuclear receptors, aNPDC-1 was found to stimulate transcription mediated by axolotl TRs, suggesting a role for aNPDC-1 in axolotl metamorphosis. Section VI: A summary of data presented in the previous sections as well as a presentation of future directions and a proposed model for NPDC-1 actions in retinoid and thyroid-receptor mediated signaling in axolotl