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jeasiq-1824
Applying some hybrid models for modeling bivariate time series assuming different distributions for random error with a practical application
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Abstract

  Bivariate time series modeling and forecasting have become a promising field of applied studies in recent times. For this purpose, the Linear Autoregressive Moving Average with exogenous variable ARMAX model is the most widely used technique over the past few years in modeling and forecasting this type of data. The most important assumptions of this model are linearity and homogenous for random error variance of the appropriate model. In practice, these two assumptions are often violated, so the Generalized Autoregressive Conditional Heteroscedasticity (ARCH) and (GARCH) with exogenous variables (GARCHX) are applied to analyze and capture the volatility that occurs in the conditional variance of a linear model. Since time series observations rarely have linear or nonlinear components in nature or usually included together. Therefore, the main purpose of this paper is to employ the hybrid model technique according to Zhang methodology for hybrid models to combine the linear forecasts of the best linear model of ARMAX models and the nonlinear forecasts of the best nonlinear models of (ARCH, GARCH & GARCHX) models and thus increase the efficiency and accuracy of performance forecasting future values of the time series.

This paper is concerned with the modeling and building of the hybrid models (ARMAX-GARCH) and (ARMAX-GARCHX), assuming three different random error distributions: Gaussian distribution, Student-t distribution, as well as the general error distribution and the last two distributions were applied for the purpose of capturing the characteristics of heavy tail distributions which have a Leptokurtic characteristic compared to the normal distribution. This research adopted a modern methodology in estimating the parameters of the hybrid model namely the (two-step procedure) methodology. In the first stage, the parameters of the linear model were estimated using three different methods: The Ordinary Least Squares method (OLS), the Recursive Least Square Method with Exponential Forgetting Factor (RLS-EF), and the Recursive Prediction Error Method (RPM). In the second stage, the parameters of the nonlinear model were estimated using the MLE method and employing the numerical improvement algorithm (BHHH algorithm).

 

 

 

The hybrid models have been applied for modeling the relationship between the exogenous time series represented by the exchange rate and the endogenous time series represented by the unemployment rate in the USA for the period from (January 2000 to December 2017 i.e. 216 observations), and also the out-of-sample forecasts of unemployment rate in the last twelve values of (2018). The forecasting performance of the hybrid models and the competing individual model was also evaluated using the loss function accuracy measures (MAPE), (MAE), and the robust (Q-LIKE). Based on statistical measurements, the results showed the hybrid models improved the accuracy and efficiency of the single model. () hybrid model error whose conditional variance follows a GED distribution is the optimal model in modeling the bivariate time series data under study and more efficient in the forecasting process compared with the individual model and the hybrid model. This is due to having the lowest values for accuracy measures. Different software packages (MATLAB (2018a), SAS 9.1, R 3.5.2 and EViews 9) were used to analyze the data under consideration.

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Publication Date
Thu Nov 01 2018
Journal Name
Al-kindy College Medical Journal
Brain Endoscopy, a big neurosurgical revolution
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Endoscopy is a rapidly growing field of Neurosurgery, it is defined as the applying of endoscope to treat different conditions of brain pathology within cerebral ventricular system and beyond it, endoscopic procedures performed by using different equipment and recording system to make a better visualization enhancing the surgeon's view by increasing illumination and magnification to look around corner and to capture image on video or digital format for later studies.

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Publication Date
Thu Feb 24 2022
Journal Name
Journal Of Educational And Psychological Researches
Statistical analysis from a Gender perspective
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This research is a theoretical study that deals with the presentation of the literature of statistical analysis from the perspective of gender or what is called Engendering Statistics. The researcher relied on a number of UN reports as well as some foreign sources to conduct the current study. Gender statistics are defined as statistics that reflect the differences and inequality of the status of women and men overall domains of life, and their importance stems from the fact that it is an important tool in promoting equality as a necessity for the process of sustainable development and the formulation of national and effective development policies and programs. The empowerment of women and the achievement of equality between men and wome

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Publication Date
Sun Aug 01 2021
Journal Name
Materials Today: Proceedings
A review of automatic history matching
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Mon Oct 01 2012
Journal Name
2012 Ieee International Conference On Circuits And Systems (iccas)
A survey of on-chip monitors
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Systems on Chips (SoCs) architecture complexity is result of integrating a large numbers of cores in a single chip. The approaches should address the systems particular challenges such as reliability, performance, and power constraints. Monitoring became a necessary part for testing, debugging and performance evaluations of SoCs at run time, as On-chip monitoring is employed to provide environmental information, such as temperature, voltage, and error data. Real-time system validation is done by exploiting the monitoring to determine the proper operation of a system within the designed parameters. The paper explains the common monitoring operations in SoCs, showing the functionality of thermal, voltage and soft error monitors. The different

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Publication Date
Thu Nov 30 2023
Journal Name
Iraqi Journal Of Science
Grey Wolf Optimization Algorithm: A Survey
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     The Gray Wolf Optimizer (GWO) is a population-based meta-heuristic algorithm  that belongs to the family of swarm intelligence algorithms inspired by the social behavior of gray wolves, in particular the social hierarchy and hunting mechanism. Because of its simplicity, flexibility, and few parameters to be tuned, it has been applied to a wide range of optimization problems. And yet it has some disadvantages, such as poor exploration skills, stagnation at local optima, and slow convergence speed. Therefore, different variants of GWO have been proposed and developed to address these disadvantages. In this article, some literature, especially from the last five years, has been reviewed and summarized by well-known publishers. Fir

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Publication Date
Sun Feb 03 2019
Journal Name
Journal Of The College Of Education For Women
Al-wakidi as a documentary historian
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This research is about the resources and the way of al-Waqidi in his
researching of al-sira of the Prophet. And what happened in the first of Islam.
This research is about the documents which al-Waqidi had it. Some of it,
which he had visited, was the places, especially the periods which the events had took
place in. He was asking those whom were contemporary to the happenings, from the
sons of al-Sahaba and al-Tabi’een.
Also this research is lightening on the new studies that gave this historian a
good respect during his work, in which he could gave the reality about his authorship.
The research is trying to draw real way of al-Waqidi and what were reported by him,
especially the documents, and what he had s

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Publication Date
Sat May 08 2021
Journal Name
Iraqi Journal Of Science
Automated Deception Detection Systems, a Review
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Humans use deception daily since it can significantly affect their life and provide a getaway solution for any undesired situation. Deception is either related to low-stakes (e.g. innocuous) or high-stakes (e.g. with harmful situations). Deception investigation importance has increased, and it became a critical issue over the years with the increase of security levels around the globe. Technology has made remarkable achievements in many human life fields, including deception detection. Automated deception detection systems (DDSs) are widely used in different fields, especially for security purposes. The DDS is comprised of multiple stages, each of which should be built/trained to perform intelligently so that the whole system can give th

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Publication Date
Tue Feb 05 2019
Journal Name
Journal Of The College Of Education For Women
A trade union movement in Britain
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Labor movement is considered important in Britain because it is an international phenomenon of the feudal system and one of the flowerings of the era of the capitalist machine. At the beginning of the 18th century, the world witnessed a change and progress in many aspects of the industrial fields such as the different means of production .this era is called the industrial revolution which especially appeared in Britain and extended to other areas of the world .it leads to many changes in Europe and participated in different economic, political and cultural and social fields. and it has a very important role in progress and development but its disadvantage is that it is exploited by the capitalists to achieve their special rights .in othe

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Publication Date
Thu Jan 14 2021
Journal Name
Iraqi Journal Of Science
FM Based Localization: A Proposed Improvement
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Localization is an essential issue in pervasive computing application. FM performs worse in some indoor environment when its structure is same to some extent the outdoor environment like shopping mall. Furthermore, FM signal are less varied over time, low power consumption and less effected by human and small object presence when it compared to Wi-Fi. Consequently, this paper focuses on FM radio signal technique and its characteristics that make it suitable to be used for indoor localization, its benefits, areas of applications and limitations.

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Publication Date
Sun Sep 30 2012
Journal Name
College Of Islamic Sciences
Surat Al-Qaria: a linguistic study
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Praise be to God, Lord of the worlds, and the best of prayers, and extradition was made to our master Muhammad and his whole family and companions:
And after:
Surat Al-Qariah is from the royal fence, which is in the thirtieth part of the Noble Qur’an. The commentators differed on the number of verses, and the reason for its naming. This surah talked about the conditions of people on the Day of Resurrection, and about how people were removed from their graves, all of which I spoke about in the preamble.
The research is divided into six topics: the first topic dealt with strange terms, while the second topic dealt with the most important audio issues mentioned in the surah, namely (slurring, advertising, substitution, and silenc

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