scholarly journals STATISTICAL ANALYSIS OF A COMPANY'S REVENUE USING TIME SERIES

2018 ◽  
Vol 6 ◽  
pp. 459-466
Author(s):  
Alexandru Eugen Stătescu

Economic and financial analysis is a method of knowing the mechanism of formation and modification of the economic phenomena through their decomposition into their component elements and by identifying the factors of influence. The object of the decomposition into elements or factors may be a result (structural analysis), or a change in the result from a basis of comparison (causal analysis).Revenue is the inflow of economic benefits during the reporting period resulted in the ordinary activity of the company as assets increase or decrease in debt that build equity excluding gains from property company contributions.The purpose of this paper is to analyze, using statistical research methods, the evolution of the income of a state owned company. For this it will be used the data from the Income and Expense Budget of METROREX S.A. on a 10-year horizon. In order to analyze the time evolution of the enterprise's revenue, it will be used the chronological series analysis methodology, the set of data from the mentioned source (namely the Income and Expense Budget of METROREX SA) and will design an econometric model with a trend and residual variable component.Time series is a form of orderly presentation of statistical data which reflect the manifestation of phenomena in a given moment or time. In other words, the time series is a sequence of values of an economic indicator or other observed over time, reflecting the process of change and development of a statistical sample in successive periods of time.Also the purpose of this paper is to build an ARMA model that fits in an appropriate way the evolution of the revenue’s time series.

2021 ◽  
pp. 30-36
Author(s):  

The use of the analysis methodology and forecasting of time series of indicators of the effectiveness of maintaining airworthiness of aircraft of civil aviation made it possible to present the dynamics of indicators as a combination of the regular component, harmonic components with oscillation periods of 12 months and more, and a random component, which represents random processes developing under the influence of groups of factors affecting the airworthiness maintenance process. The results obtained are aimed at improving the safety and effectiveness of aircraft use. Keywords: aircraft, airworthiness, effectiveness of airworthiness maintenance, analysis methodology, forecasting, time series of effectiveness indicators. [email protected]


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Chang-Sheng Lin ◽  
Dar-Yun Chiang ◽  
Tse-Chuan Tseng

Modal Identification is considered from response data of structural systems under nonstationary ambient vibration. The conventional autoregressive moving average (ARMA) algorithm is applicable to perform modal identification, however, only for stationary-process vibration. The ergodicity postulate which has been conventionally employed for stationary processes is no longer valid in the case of nonstationary analysis. The objective of this paper is therefore to develop modal-identification techniques based on the nonstationary time series for linear systems subjected to nonstationary ambient excitation. Nonstationary ARMA model with time-varying parameters is considered because of its capability of resolving general nonstationary problems. The parameters of moving averaging (MA) model in the nonstationary time-series algorithm are treated as functions of time and may be represented by a linear combination of base functions and therefore can be used to solve the identification problem of time-varying parameters. Numerical simulations confirm the validity of the proposed modal-identification method from nonstationary ambient response data.


Author(s):  
YU-YUN HSU ◽  
SZE-MAN TSE ◽  
BERLIN WU

In recent years, the innovation and improvement of forecasting techniques have caught more and more attention. Especially, in the fields of financial economics, management planning and control, forecasting provides indispensable information in decision-making process. If we merely use the time series with the closing price array to build a forecasting model, a question that arises is: Can the model exhibit the real case honestly? Since, the daily closing price of a stock index is uncertain and indistinct. A decision for biased future trend may result in the danger of huge lost. Moreover, there are many factors that influence daily closing price, such as trading volume and exchange rate, and so on. In this research, we propose a new approach for a bivariate fuzzy time series analysis and forecasting through fuzzy relation equations. An empirical study on closing price and trading volume of a bivariate fuzzy time series model for Taiwan Weighted Stock Index is constructed. The performance of linguistic forecasting and the comparison with the bivariate ARMA model are also illustrated.


2021 ◽  
Author(s):  
Ines Sansa ◽  
Najiba Mrabet Bellaaj

Solar radiation is characterized by its fluctuation because it depends to different factors such as the day hour, the speed wind, the cloud cover and some other weather conditions. Certainly, this fluctuation can affect the PV power production and then its integration on the electrical micro grid. An accurate forecasting of solar radiation is so important to avoid these problems. In this chapter, the solar radiation is treated as time series and it is predicted using the Auto Regressive and Moving Average (ARMA) model. Based on the solar radiation forecasting results, the photovoltaic (PV) power is then forecasted. The choice of ARMA model has been carried out in order to exploit its own strength. This model is characterized by its flexibility and its ability to extract the useful statistical properties, for time series predictions, it is among the most used models. In this work, ARMA model is used to forecast the solar radiation one year in advance considering the weekly radiation averages. Simulation results have proven the effectiveness of ARMA model to forecast the small solar radiation fluctuations.


Author(s):  
T. T. Wong ◽  
C. W. Leung

Recent advances in the applications of ANN have demonstrated successful cases in time series analysis, data mining, civil engineering, financial analysis, music creation, fishing prediction, production scheduling, intruder detection, etc., making them an important tool for research and development[1]. ANN and evolutionary computation(EC) techniques have been employed successfully in solving real-world problems including those with a temporal component[2]. In another work[3], a hybrid method based on a combination of evolutionary computation and neural network(NN) has been used to predict time series. In the world of databases, various ANN-based strategies have been used for knowledge search and extraction[4]. Intelligent neural systems have been constructed with the aid of genetic algorithm-based EC techniques and these systems have been applied in breast cancer diagnosis[5]. Genetic algorithms(GA) have been applied to develop a general method of selecting the most relevant subset of variables in the field of analytical chemistry to classify apple beverages[6]. New ANN methods enable civil engineers to use computing in different ways. Besides as a tool in urban storm drainage[7], ANN and Genetic Programming(GP) have been implemented in the prediction and modelling of the flow of a typical urban basin [8]. In the latter case, it was shown that these two techniques could be combined in order to design a real-time alarm system for floods or subsidence warning in various types of urban basins. ANN models for consistency, measured by slump, in the case of conventional concrete have also been developed[9]. In a time series prediction of the quarterly values of the medical component of the Consumer Price Index(CPI), the results obtained with both neural and functional networks have been shown to be quite similar[10]. Dimensionality reduction, variable reduction, hybrid networks, normal fuzzy and ANN have been applied to predict bond rating[11]. A recent online survey through the ISI Web of Knowledge using keywords such as “ANN” and “thermal design” would reveal only ten relevant SCI publications[12]. In the area of food processing, ANN was used to predict the maximum or minimum temperature reached in the sample after pressurization and the time needed for thermal re-equilibration[13]. The accurate determination of thermophysical properties of milk is very important for design, simulation, optimization, and control of food processing such as evaporation, heat exchanging, spray drying, and so forth. Generally, polynomial methods are used for prediction of these properties based on empirical correlation to experimental data. However, it was found that ANN presented a better prediction capability of specific heat, thermal conductivity, and density of milk than polynomial modeling and it was suggested as a reasonable alternative to empirical modeling for thermophysical properties of foods[14]. Numerical simulation of natural circulation boiling water reactor is important in order to study its performance for different designs and under various off-design conditions. It was found that very fast numerical simulations, useful for extensive parametric studies and for solving design optimization problems, can be achieved by using an ANN model of the system[15]. ANN models and GA were applied for developing prediction models and for optimization of constant temperature retort thermal processing of conduction heating foods[16]. ANN technique has been used as a new approach to determine the exergy losses of an ejector-absorption heat transformer (EAHT)[17]. The results show that the ANN approach has the advantages of computational speed, low cost for feasibility, rapid turnaround, which is especially important during iterative design phases, and easy of design by operators with little technical experience. Computational fluid dynamics approach is often employed for heat transfer analysis of a ball grid array(BGA) package that is widely used in the modern electronics industry. Owing to the complicated geometric configuration of the BGA package, an ANN was trained to establish the relationship between the geometry input and the thermal resistance output[18]. The results of this study provide the electronic packaging industry with a reliable and rapid method for heat dissipation design of BGA packages. Thermal spraying is a versatile technique of coating manufacturing implementing large variety of materials and processes. An ANN was developed to relate processing parameters to properties of alumina-titania ceramic coatings[19]. Predicted results show globally a well agreement with the experimental values. It can be seen that applications of ANN in thermal design is scarce and this article aims to explore the application of an ANN in gas-fired cooktop burner design.


2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Md. Rabiul Islam ◽  
Md. Rashed-Al-Mahfuz ◽  
Shamim Ahmad ◽  
Md. Khademul Islam Molla

This paper presents a subband approach to financial time series prediction. Multivariate empirical mode decomposition (MEMD) is employed here for multiband representation of multichannel financial time series together. Autoregressive moving average (ARMA) model is used in prediction of individual subband of any time series data. Then all the predicted subband signals are summed up to obtain the overall prediction. The ARMA model works better for stationary signal. With multiband representation, each subband becomes a band-limited (narrow band) signal and hence better prediction is achieved. The performance of the proposed MEMD-ARMA model is compared with classical EMD, discrete wavelet transform (DWT), and with full band ARMA model in terms of signal-to-noise ratio (SNR) and mean square error (MSE) between the original and predicted time series. The simulation results show that the MEMD-ARMA-based method performs better than the other methods.


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