Bayesian Tobit quantile regression using-prior distribution with ridge parameter

A Bayesian approach is proposed for coefficient estimation in the Tobit quantile regression model. The proposed approach is based on placing a g-prior distribution depends on the quantile level on the regression coefficients. The prior is generalized by introducing a ridge parameter to address important challenges that may arise with censored data, such as multicollinearity and overfitting problems. Then, a stochastic search variable selection approach is proposed for Tobit quantile regression model based on g-prior. An expression for the hyperparameter g is proposed to calibrate the modified g-prior with a ridge parameter to the corresponding g-prior. Some possible extensions of the proposed approach are discussed, including the continuous and binary responses in quantile regression. The methods are illustrated using several simulation studies and a microarray study. The simulation studies and the microarray study indicate that the proposed approach performs well

Should Private Expectations Concern Central Bankers? *

Abstract We analyze the standard New Keynesian economy adjusted by a financial intermediation sector, heterogenous, imperfect knowledge, and adaptive learning. We consider two groups of agents (i) private agents (households, firms, private banks) and (ii) the central bank who differ in their knowledge and expectations. The monetary-policy transmission is non-trivial in this environment. The interest rate directly affecting the decisions of households and firms is influenced by the private banks expectations, and the monetary policy may get distorted. The basic finding suggests the higher knowledge heterogeneity, the less active monetary policy should be in order to stabilize the economy. This contrasts the standard literature with homogenous knowledge and expectations. Abstrakt V tomto článku zkoumáme ekonomickou dynamiku v kontextu nového keynesiánského modelu rozšířeného o finanční sektor, heterogenní, nedokonalou informaci a adaptivní učení. Rozlišujeme dvě skupiny ekonomických agentů: (i) soukromé agenty (domácnosti, firmy a soukromé banky) a (ii) centrální banku. U obou skupin předpokládáme odlišné znalosti a očekávání. V tomto prostředí už to není centrální banka, která má přímý vliv na ekonomiku, ale jsou to soukromé banky. Jejich úrokové sazby nyní vstupují do rozhodování domácností a firem. Trasmise monetární politiky se tak stává netriviální. Původní záměr centrální banky, např. cílovat inflaci, může být vychýlen sazbami soukromých bank, které je stanovují na základě vlastní informace a očekávání. V analýze docházíme k závěru, který je v kontrastu s literaturou pracující s homegnní, nedokonalou informací. Čím větší je rozdíl znalostí mezi oběma skupinami agentů, tím méně by měla monetarní politika být aktivní. Snižuje se tak variabilita ekonomických veličin a zrychluje se konvergence do ekonomické rovnováhy při dokonalé informaci

Continuous belief functions and α-stable distributions

International audienceThe theory of belief functions has been formalized in continuous domain for pattern recognition. Some applications use assumption of Gaussian models. However, this assumption is reductive. Indeed, some data are not symmetric and present property of heavy tails. It is possible to solve these problems by using a class of distributions called α-stable distributions. Consequently, we present in this paper a way to calculate pignistic probabilities with plausibility functions where the knowledge of the sources of information is represented by symmetric α-stable distributions. To validate our approach, we compare our results in special case of Gaussian distributions with existing methods. To illustrate our work, we generate arbitrary distributions which represents speed of planes and take decisions. A comparison with a Bayesian approach is made to show the interest of the theory of belief functions

The effect of phase chemistry on the extent of strengthening mechanisms in model Ni-Cr-Al-Ti-Mo based superalloys

The exceptional mechanical properties of polycrystalline nickel-based superalloys arise through various concurrent strengthening mechanisms. Whilst these mechanisms are generally understood, consensus has yet to be established on the precise contribution of each to the overall alloy strength. Furthermore, changes in alloy chemistry influence several different mechanisms, making the assessment of individual alloying elements complex. In this study, a series of model quinary Ni-based superalloys has been investigated to systematically study the effect of varying Mo content on the contributing strengthening mechanisms. Using microstructural data, the yield strength was modelled by summing the individual effects of solid solution in both the γ and γ ' phases, coherency, grain boundary and precipitation strengthening. The total predicted yield stress increased with Mo content despite the diminishing contribution of precipitation strengthening. It is shown that solid solution strengthening of the ordered γ' precipitate phase is a key contributor to the overall strength, and that variations in composition between the tertiary and secondary γ ' lead to significant changes in mechanical properties that should be accounted for in models of alloy strength.Funding was provided by the EPSRC/Rolls-Royce Strategic Partnership under EP/M005607/1 and EP/H022309/1. The Oxford Atom Probe facility was funded by the EPSRC under EP/M022803/1. E. I. Galindo-Nava would like to acknowledge the Royal Academy of Engineering for his fellowship funding. Neutron diffraction beam time was supported through the Canadian Neutron Beam Centre under Experiment number 1258

New constraints on Lyman-α opacity with a sample of 62 quasars at z > 5.7

We present measurements of the mean and scatter of the IGM Lyman-{\alpha} opacity at 4.9 5.7, the largest sample assembled at these redshifts to date by a factor of two. The sample size enables us to sample cosmic variance at these redshifts more robustly than ever before. The spectra used here were obtained by the SDSS, DES-VHS and SHELLQs collaborations, drawn from the ESI and X-Shooter archives, reused from previous studies or observed specifically for this work. We measure the effective optical depth of Lyman-{\alpha} in bins of 10, 30, 50 and 70 cMpc h-1, construct cumulative distribution functions under two treatments of upper limits on flux and explore an empirical analytic fit to residual Lyman-{\alpha} transmission. We verify the consistency of our results with those of previous studies via bootstrap re-sampling and confirm the existence of tails towards high values in the opacity distributions, which may persist down to z = 5.2. Comparing our results with predictions from cosmological simulations, we find further strong evidence against models that include a spatially uniform ionizing background and temperature-density relation. We also compare to IGM models that include either a fluctuating UVB dominated by rare quasars or temperature fluctuations due to patchy reionization. Although both models produce better agreement with the observations, neither fully captures the observed scatter in IGM opacity. Our sample of 62 z > 5.7 quasar spectra opens many avenues for future study of the reionisation epoch

Preoperative localisation for parathyroid surgery in primary hyperparathyroidism: a study to evaluate the clinical utility of different imaging modalities

Primary hyperparathyroidism (PHPT) is caused by a solitary benign adenoma in 80‐85% of cases, but may also be due to multi‐gland or ectopic disease, hyperplasia, and rarely parathyroid carcinoma. Preoperative localisation studies are important to identify patients suitable for minimally invasive parathyroid surgery. The aim of this study was to evaluate the accuracy of ultrasound (US), parathyroid scintigraphy (MIBI) and computed tomography (CT) utilised in the preoperative setting in a district general hospital, with limited access to single photon‐emission computed tomography (SPECT)

Men's experiences of radiotherapy treatment for localized prostate cancer and its long-term treatment side effects: a longitudinal qualitative study.

PURPOSE: To investigate men's experiences of receiving external-beam radiotherapy (EBRT) with neoadjuvant Androgen Deprivation Therapy (ADT) for localized prostate cancer (LPCa) in the ProtecT trial. METHODS: A longitudinal qualitative interview study was embedded in the ProtecT RCT. Sixteen men with clinically LPCa who underwent EBRT in ProtecT were purposively sampled to include a range of socio-demographic and clinical characteristics. They participated in serial in-depth qualitative interviews for up to 8 years post-treatment, exploring experiences of treatment and its side effects over time. RESULTS: Men experienced bowel, sexual, and urinary side effects, mostly in the short term but some persisted and were bothersome. Most men downplayed the impacts, voicing expectations of age-related decline, and normalizing these changes. There was some reticence to seek help, with men prioritizing their relationships and overall health and well-being over returning to pretreatment levels of function. Some unmet needs with regard to information about treatment schedules and side effects were reported, particularly among men with continuing functional symptoms. CONCLUSIONS: These findings reinforce the importance of providing universal clear, concise, and timely information and supportive resources in the short term, and more targeted and detailed information and care in the longer term to maintain and improve treatment experiences for men undergoing EBRT

Characteristics of men responding to an invitation to undergo testing for prostate cancer as part of a randomised trial

Background: Sociodemographic characteristics are associated with participating in cancer screening and trials. We compared the characteristics of those responding with those not responding to a single invitation for prostate-specific antigen (PSA) testing for prostate cancer as part of the Cluster randomised triAl of PSA testing for Prostate cancer (CAP). / Methods: Age, rurality and deprivation among 197,763 men from 271 cluster-randomised primary care centres in the UK were compared between those responding (n = 90,300) and those not responding (n = 100,953) to a prostate cancer testing invitation. / Results: There was little difference in age between responders and nonresponders. Responders were slightly more likely to come from urban rather than rural areas and were slightly less deprived than those who did not respond. / Conclusion: These data indicate similarities in age and only minor differences in deprivation and urban location between responders and nonresponders. These differences were smaller, but in the same direction as those observed in other screening trials. / Trial registration: ISRCTN92187251. Registered on 29 November 2004

Wilson Lines and a Canonical Basis of SU(4) Heterotic Standard Models

The spontaneous breaking of SU(4) heterotic standard models by Z_3 x Z_3 Wilson lines to the MSSM with three right-handed neutrino supermultiplets and gauge group SU(3)_C x SU(2)_L x U(1) x U(1) is explored. The two-dimensional subspace of the Spin(10) Lie algebra that commutes with su(3)_C + su(2)_L is analyzed. It is shown that there is a unique basis for which the initial soft supersymmetry breaking parameters are uncorrelated and for which the U(1) x U(1) field strengths have no kinetic mixing at any scale. If the Wilson lines "turn on" at different scales, there is an intermediate regime with either a left-right or a Pati-Salam type model. We compute their spectra directly from string theory, and adjust the associated mass parameter so that all gauge parameters exactly unify. A detailed analysis of the running gauge couplings and soft gaugino masses is presented.Comment: 59 pages, 9 figure