Preferred Language
Articles
/
jeasiq-1824
Applying some hybrid models for modeling bivariate time series assuming different distributions for random error with a practical application
...Show More Authors

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.

Crossref
View Publication Preview PDF
Quick Preview PDF
Publication Date
Wed Oct 07 2020
Journal Name
Journal Of Interdisciplinary Mathematics
Discrete an SIS model with immigrants and treatment
...Show More Authors

In this paper, a discrete SIS epidemic model with immigrant and treatment effects is proposed. Stability analysis of the endemic equilibria and disease-free is presented. Numerical simulations are conformed the theoretical results, and it is illustrated how the immigrants, as well as treatment effects, change current model behavior

View Publication Preview PDF
Scopus (12)
Crossref (6)
Scopus Crossref
Publication Date
Thu Jan 16 2020
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Fulfill the Requirements of Financial Authority For Adoption Of Financial statements in determining The Tax Base: بحث تطبيقي في الهيئة العامة للضرائب لعينة من الشركات المحدودة
...Show More Authors

The Financial authority is considered as one of  the most of benefited parts from financial statements  which depends on it in process of accounting  in taxes as basis to determine The Tax Base , but no confidence from financial authority part in objectivity of income financial information in them for many of limited companies led to no dependence on them to specify taxation contain & dependence on yearly regulations that issued them. To enhance the confidence of financial authority to these lists must meet its requirements, because the menus Fulfill the requirements of the financial authority increases the confidence in these statements and therefore reliable in determining the tax base. So this research aims to speci

... Show More
View Publication Preview PDF
Publication Date
Fri Sep 30 2011
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Vapor-Liquid-Liquid Equilibrium (VLLE) Data for the Systems Ethyl acetate + Water, Toluene + Water and Toluene + Ethyl acetate + Water at 101.3 kPa. Using Modified Equilibrium Still
...Show More Authors

Isobaric Vapor-Liquid-Liquid equilibrium data for the binary systems ethyl acetate + water, toluene + water and the ternary system toluene + ethyl acetate + water were determined by a modified equilibrium still, the still consisted of a boiling and a condensation sections supplied with mixers that helped to correct the composition of the recycled condensed liquid and the boiling temperature readings in the condensation and boiling sections respectively. The VLLE data where predicted and correlated using the Peng-Robinson Equation of State in the vapor phase and one of the activity coefficient models Wilson, NRTL, UNIQUAC and the UNIFAC in the liquid phase and also were correlated using the Peng-Robinson Equation of State in both the vapo

... Show More
View Publication Preview PDF
Publication Date
Mon Oct 22 2018
Journal Name
Journal Of Economics And Administrative Sciences
Quality of working life, Job enrichment and its impact on knowledge capital: exploratory study for opinion of Faculty Members at government and Private Colleges on Baghdad
...Show More Authors

      The problem of research was the lack of research that dealt with issue of the organizational environment, job design approach that is more suitable for knowledge work, therefore, the research aims to determine the impact of quality of working life and  job enrichment on knowledge capital, starting from the hypothesis that there significant impact of quality of working life and job enrichment on knowledge capital, to achieve this goal the researcher from the theoretical literature and related studies conclude to the construction of the scheme shows the hypothetical relationship between the variables, which was adopted quality of working life and job enrichment as independent variable while knowl

... Show More
View Publication Preview PDF
Crossref
Publication Date
Mon Jan 01 2018
Journal Name
الأستاذ
Analysis of the content of the chemistry book for the second intermediate grade according to habits of mind In light of the educational reform project (2061)
...Show More Authors

Preview PDF
Publication Date
Sun May 30 2021
Journal Name
Indian Journal Of Forensic Medicine & Toxicology,
Effect of Diabetes and Hypertension on Right Carotid Artery Intima Media Thickness and Variable Spectral Waveform Indices And Parameters in Relation To Age for Iraqi Patients
...Show More Authors

Background: Arterial stiffness is related with atherosclerosis and cardiovascular disease events. Patients with atherosclerotic disease show to have larger diameters, reduced arterial compliance and lower flow velocities. Aim of study : To compare between patients of two age groups with concomitant diseases diabetes and hypertension in regard to intima media thickness and blood flow characteristics in order to estimate the blood perfusion to the brain via the common and internal carotid arteries. Subject and Methods : 40 patients with (diabetic and hypertension) diseases were enrolled , they were classified according to age. Color Doppler and B mode ultrasound was used to determine lumen Diameter (D), Intima – media thickness (IMT)

... Show More
Scopus (1)
Scopus
Publication Date
Sat Mar 01 2014
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Obstacles to the adoption of business commercial books to determine taxable income and ways to address them: An applied research at The General Commission for Taxes
...Show More Authors

The research aims to shed light on the obstacles that hinder the use of taxpayers' commercial books covered by provisions of the amended commercial book-keeping system No. 2 of 1985 and ways to address these obstacles. On this basis, the main null hypothesis was formulated that there is no statistically significant relationship between the obstacles to the adoption of the commercial books and taxable income.

The research data were collected on the base of three applied case studies of registered taxpayers in the General Commission of Taxes, GCT, together with the use of a questionnaire distributed to a sample of taxpayers ( companies ). The collected data were analyzed, the result  were presented  and the hypothesis was

... Show More
View Publication Preview PDF
Publication Date
Sat Jun 30 2018
Journal Name
College Of Islamic Sciences
Inform the people of the Enlightenment including what was said in detail In photography For Mohammed Hashim bin Ahmed footy famous Balva Hashim (Tel: 1349 e)
...Show More Authors

Inform the people of the Enlightenment including what was said in detail
In photography
For Mohammed Hashim bin Ahmed footy famous Balva Hashim (Tel: 1349 e)

View Publication Preview PDF
Publication Date
Wed Sep 17 2025
Journal Name
Al–bahith Al–a'alami
The Semiology of Narrative Construction in Television Advertising to an Announce "God Will not Forget us" about the Covid-19 Pandemic for Zain Mobile Telecommunication Company
...Show More Authors

This research paper tries to show the significance of the narrative structure in the television advertisement and its connotations. The researchers chose the annual advertisement of Zain Mobile Telecommunication Company for the year 2020, which shed light on the global Corona pandemic crisis. The idea of the advertisement won wide approval as it focused on the suffering that everyone is witnessing like medical and security personnel in particular, and family relationships consequences.
In addition to the positive global interaction with the message presented by the Company in these exceptional circumstances. The advertisement, which lasted for 2.35 minutes, exceeded 13 million views in a short period of time. This prompted us to choos

... Show More
View Publication Preview PDF
Crossref
Publication Date
Mon Jan 01 2024
Journal Name
Iraqi Journal Of Hematology
Provisional diagnosis of clinically significant hemoglobinopathies and decision on suitability for marriage as part of the premarital screening program in Iraq: Iraqi Society of Hematology Guidelines
...Show More Authors

View Publication
Crossref (1)
Clarivate Crossref