scholarly journals Correction to: Forecasting International Sugar Prices: A Bayesian Model Average Analysis

Sugar Tech ◽  
2021 ◽  
Author(s):  
El Mamoun Amrouk ◽  
Thomas Heckelei
Sugar Tech ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 552-562
Author(s):  
El Mamoun Amrouk ◽  
Thomas Heckelei

Ocean Science ◽  
2012 ◽  
Vol 8 (2) ◽  
pp. 211-226 ◽  
Author(s):  
B. Pérez ◽  
R. Brouwer ◽  
J. Beckers ◽  
D. Paradis ◽  
C. Balseiro ◽  
...  

Abstract. ENSURF (Ensemble SURge Forecast) is a multi-model application for sea level forecast that makes use of several storm surge or circulation models and near-real time tide gauge data in the region, with the following main goals: 1. providing easy access to existing forecasts, as well as to its performance and model validation, by means of an adequate visualization tool; 2. generation of better forecasts of sea level, including confidence intervals, by means of the Bayesian Model Average technique (BMA). The Bayesian Model Average technique generates an overall forecast probability density function (PDF) by making a weighted average of the individual forecasts PDF's; the weights represent the Bayesian likelihood that a model will give the correct forecast and are continuously updated based on the performance of the models during a recent training period. This implies the technique needs the availability of sea level data from tide gauges in near-real time. The system was implemented for the European Atlantic facade (IBIROOS region) and Western Mediterranean coast based on the MATROOS visualization tool developed by Deltares. Results of validation of the different models and BMA implementation for the main harbours are presented for these regions where this kind of activity is performed for the first time. The system is currently operational at Puertos del Estado and has proved to be useful in the detection of calibration problems in some of the circulation models, in the identification of the systematic differences between baroclinic and barotropic models for sea level forecasts and to demonstrate the feasibility of providing an overall probabilistic forecast, based on the BMA method.


Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1341 ◽  
Author(s):  
Yen-Ming Chiang ◽  
Ruo-Nan Hao ◽  
Jian-Quan Zhang ◽  
Ying-Tien Lin ◽  
Wen-Ping Tsai

Sustainable water resources management is facing a rigorous challenge due to global climate change. Nowadays, improving streamflow predictions based on uneven precipitation is an important task. The main purpose of this study is to integrate the ensemble technique concept into artificial neural networks for reducing model uncertainty in hourly streamflow predictions. The ensemble streamflow predictions are built following two steps: (1) Generating the ensemble members through disturbance of initial weights, data resampling, and alteration of model structure; (2) consolidating the model outputs through the arithmetic average, stacking, and Bayesian model average. This study investigates various ensemble strategies on two study sites, where the watershed size and hydrological conditions are different. The results help to realize whether the ensemble methods are sensitive to hydrological or physiographical conditions. Additionally, the applicability and availability of the ensemble strategies can be easily evaluated in this study. Among various ensemble strategies, the best ESP is produced by the combination of boosting (data resampling) and Bayesian model average. The results demonstrate that the ensemble neural networks greatly improved the accuracy of streamflow predictions as compared to a single neural network, and the improvement made by the ensemble neural network is about 19–37% and 20–30% in Longquan Creek and Jinhua River watersheds, respectively, for 1–3 h ahead streamflow prediction. Moreover, the results obtained from different ensemble strategies are quite consistent in both watersheds, indicating that the ensemble strategies are insensitive to hydrological and physiographical factors. Finally, the output intervals of ensemble streamflow prediction may also reflect the possible peak flow, which is valuable information for flood prevention.


Author(s):  
Hồ Quang Thanh ◽  
Hoàng Trọng Vinh ◽  
Trần Tuấn

Nghiên cứu này xem xét các yếu tố kinh tế vĩ mô tác động đến giảm nghèo của tỉnh Lâm Đồng, được xác định trên cơ sở xây dựng mô hình hồi qui bội tối ưu bằng phương pháp BMA (Bayesian Model Average) dựa vào kết quả các chỉ số về thu nhập, thất nghiệp (việc làm), lạm phát và chất lượng nguồn nhân lực tại Lâm Đồng. Kết quả nghiên cứu đã tìm thấy 2 yếu tố quan trọng, có ý nghĩa thống kê và giá trị thực tiễn tác động đến giảm nghèo của tỉnh Lâm Đồng theo mức độ tầm quan trọng của từng trọng số, đó là: Thu nhập bình quân và Chất lượng nguồn nhân lực. Cuối cùng tác giả trình bày hàm ý và khuyến nghị một số giải pháp từ kết quả nghiên cứu.


2018 ◽  
Vol 228 ◽  
pp. 01002
Author(s):  
Ying Zhang

Based on the study of Bayesian model average (BMA), this paper proposes to mix the prior distribution and sampling distribution to obtain the average method of the mixed sampling distribution Bayesian model overcoming the problem that traditional econometric modeling method does not explicitly consider the uncertainty of the model. If all the alternative models have the same parametric form, then the new Bayesian estimation will degenerate into the BMA estimator. The empirical results show that the method is better than Bayesian model average.


2020 ◽  
Vol 21 (10) ◽  
pp. 2401-2418 ◽  
Author(s):  
E. C. Massoud ◽  
H. Lee ◽  
P. B. Gibson ◽  
P. Loikith ◽  
D. E. Waliser

AbstractThis study utilizes Bayesian model averaging (BMA) as a framework to constrain the spread of uncertainty in climate projections of precipitation over the contiguous United States (CONUS). We use a subset of historical model simulations and future model projections (RCP8.5) from the Coupled Model Intercomparison Project phase 5 (CMIP5). We evaluate the representation of five precipitation summary metrics in the historical simulations using observations from the NASA Tropical Rainfall Measuring Mission (TRMM) satellites. The summary metrics include mean, annual and interannual variability, and maximum and minimum extremes of precipitation. The estimated model average produced with BMA is shown to have higher accuracy in simulating mean rainfall than the ensemble mean (RMSE of 0.49 for BMA versus 0.65 for ensemble mean), and a more constrained spread of uncertainty with roughly a third of the total uncertainty than is produced with the multimodel ensemble. The results show that, by the end of the century, the mean daily rainfall is projected to increase for most of the East Coast and the Northwest, may decrease in the southern United States, and with little change expected for the Southwest. For extremes, the wettest year on record is projected to become wetter for the majority of CONUS and the driest year to become drier. We show that BMA offers a framework to more accurately estimate and to constrain the spread of uncertainties of future climate, such as precipitation changes over CONUS.


2020 ◽  
Vol 8 (5) ◽  
pp. 68-80
Author(s):  
Le Dinh Thang ◽  
Nguyen Van Si

Purpose of the study: this paper aims to determine factors affecting the willingness to join crop insurance. Besides, this paper is the purpose of developing a coffee tree insurance program. Methodology: The authors used a systematic random sampling technique. The authors used the Bayesian Model Average (BMA) that calculated the probability of all independent variables affecting the dependent variable with significance level 0.05. Besides, the data based on 480 coffee farmers in Dak Lak province, Vietnam. Main Findings: Authors calculated the probability of all independent variables affecting the dependent variable with significance level 0.05. Independent variables, including loans, drought risks, educational level, experiences, and productivity. Applications of this study: This result is a vital science document for insurance companies and managers to apply and suggest recommendations for developing coffee tree insurance in the future. Novelty/Originality of this study: Vietnam is an agricultural country, 60-70% of the population lives in rural areas, and agricultural insurance should have a considerable market. Farmers’ agrarian insurance cultivated the coffee trees that are currently underdeveloped and challenging.  


Econometrics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 17
Author(s):  
Dimitris Fouskakis ◽  
Ioannis Ntzoufras

This paper focuses on the Bayesian model average (BMA) using the power–expected– posterior prior in objective Bayesian variable selection under normal linear models. We derive a BMA point estimate of a predicted value, and present computation and evaluation strategies of the prediction accuracy. We compare the performance of our method with that of similar approaches in a simulated and a real data example from economics.


1981 ◽  
Vol 20 (03) ◽  
pp. 174-178 ◽  
Author(s):  
A. I. Barnett ◽  
J. Cynthia ◽  
F. Jane ◽  
Nancy Gutensohn ◽  
B. Davies

A Bayesian model that provides probabilistic information about the spread of malignancy in a Hodgkin’s disease patient has been developed at the Tufts New England Medical Center. In assessing the model’s reliability, it seemed important to use it to make predictions about patients other than those relevant to its construction. The accuracy of these predictions could then be tested statistically. This paper describes such a test, based on 243 Hodgkin’s disease patients of known pathologic stage. The results obtained were supportive of the model, and the test procedure might interest those wishing to determine whether the imperfections that attend any attempt to make probabilistic forecasts have gravely damaged their accuracy.


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