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Wyświetlanie 1-15 z 62
Tytuł:
A study of parallel techniques for dimensionality reduction and its impact on the quality of text processing algorithms
Autorzy:
Pietroń, M.
Wielgosz, M.
Karwatowski, M.
Wiatr, K.
Powiązania:
https://bibliotekanauki.pl/articles/114190.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
singular value decomposition
vector space model
TFIDF
Opis:
The presented algorithms employ the Vector Space Model (VSM) and its enhancements such as TFIDF (Term Frequency Inverse Document Frequency) with Singular Value Decomposition (SVD). TFIDF were applied to emphasize the important features of documents and SVD was used to reduce the analysis space. Consequently, a series of experiments were conducted. They revealed important properties of the algorithms and their accuracy. The accuracy of the algorithms was estimated in terms of their ability to match the human classification of the subject. For unsupervised algorithms the entropy was used as a quality evaluation measure. The combination of VSM, TFIDF, and SVD came out to be the best performing unsupervised algorithm with entropy of 0.16.
Źródło:
Measurement Automation Monitoring; 2015, 61, 7; 352-353
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current aspects of mathematical modelling of evaluating quality of agricultural products
Autorzy:
Lysa, O.
Powiązania:
https://bibliotekanauki.pl/articles/410740.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
target function
fuzzy restriction
vector-optimizing model
Opis:
The paper presents mathematical model of complex evaluation of the quality of production with optimizing indicators of crop growing. Multicriterion model is reduced to the problem of optimizing with the predetermined target function which considers almost all parameters of the prodution quality. The model takes into account limits of modifications of quality characteristics of production by introducing the indistinct description of the quality characteristics of productions. The model was developed on the example of evaluating quality of the barley grain.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2014, 3, 4; 59-62
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laboratory vector models in regard to animal protection legislation
Autorzy:
Lonc, E
Mizgajska, H.
Hildebrand, J.
Powiązania:
https://bibliotekanauki.pl/articles/839787.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Parazytologiczne
Tematy:
legislation
laboratory vector model
International Committee for Laboratory Animals
parasitology
animal protection
Źródło:
Annals of Parasitology; 1999, 45, 4
0043-5163
Pojawia się w:
Annals of Parasitology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oddziaływanie inflacji na wzrost gospodarczy w Polsce w okresie 1991-2009
The impact of inflation on economic growth in Poland in the period 1991-2009
Autorzy:
Misztal, P.
Powiązania:
https://bibliotekanauki.pl/articles/399322.pdf
Data publikacji:
2010
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
inflacja
wzrost gospodarczy
model autoregresji wektorowej
inflation
economic growth
vector autoregression model
Opis:
The main aim of the study was to analyze the impact of inflation on the economic growth in Poland in the period from 1991 to 2009. In the paper, methods based on the literature study of international economics and international finance as well as econometric methods (Vector Autoregression Model - VAR) were used. All statistics used in the paper came from the statistical base EconStats. On the basis of the analysis of the relationship between inflation and the economic growth in Poland in the period from 1991 to 2009 you can point to several key conclusions. Firstly, relationship between the inflation rate and the dynamics of real GDP in Poland was relatively important in this period. Moreover, on the basis of VAR model estimates, a negative influence of inflation on the economic growth in Poland over considered period was confirmed. The results also revealed that changes in the inflation rate accounted for 0.5% variability of the growth rate of real GDP in Poland after a year from the shock. Moreover, the existence of non-linear relationship between inflation and economic growth in Poland was confirmed and two threshold levels of inflation amounted to 2.49% and 11.8% were estimated.
Źródło:
Ekonomia i Zarządzanie; 2010, 2, 3; 46-57
2080-9646
Pojawia się w:
Ekonomia i Zarządzanie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of budget deficits and macroeconomic fundamentals: A VAR-VECM approach
Autorzy:
Epaphra, Manamba
Powiązania:
https://bibliotekanauki.pl/articles/522020.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Ekonomiczny w Katowicach
Tematy:
Budget deficit
Macroeconomic variables
Vector Autoregression
Vector Error-Correction Model
Opis:
Aim/purpose – This paper examines the relationship between budget deficits and selected macroeconomic variables in Tanzania for the period spanning from 1966 to 2015. Design/methodology/approach – The paper uses Vector autoregression (VAR) – Vector Error Correction Model (VECM) and variance decomposition techniques. The Johansen’s test is applied to examine the long run relationship among the variables under study. Findings – The Johansen’s test of cointegration indicates that the variables are cointegrated and thus have a long run relationship. The results based on the VAR-VECM estimation show that real GDP and exchange rate have a negative and significant relationship with budget deficit whereas inflation, money supply and lending interest rate have a positive one. Variance decomposition results show that variances in the budget deficits are mostly explained by the real GDP, followed by inflation and real exchange rate. Research implications/limitations – Results are very indicative, but highlight the importance of containing inflation and money supply to check their effects on budget deficits over the short run and long-run periods. Also, policy recommendation calls for fiscal authorities in Tanzania to adopt efficient and effective methods of tax collection and public sector spending. Originality/value/contribution – Tanzania has been experiencing budget deficit since the 1970s and that this budget deficit has been blamed for high indebtedness, inflation and poor investment and growth. The paper contributes to the empirical debate on the causal relationship between budget deficits and macroeconomic variables by employing VAR-VECM and variance decomposition approaches.
Źródło:
Journal of Economics and Management; 2017, 30; 20-57
1732-1948
Pojawia się w:
Journal of Economics and Management
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Document Clustering : Concepts, Metrics and Algorithms
Autorzy:
Tarczynski, T.
Powiązania:
https://bibliotekanauki.pl/articles/226231.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
document clustering
text mining
k-means
hierarchical clustersting
vector space model
Opis:
Document clustering, which is also refered to as text clustering, is a technique of unsupervised document organisation. Text clustering is used to group documents into subsets that consist of texts that are similar to each orher. These subsets are called clusters. Document clustering algorithms are widely used in web searching engines to produce results relevant to a query. An example of practical use of those techniques are Yahoo! hierarchies of documents [1]. Another application of document clustering is browsing which is defined as searching session without well specific goal. The browsing techniques heavily relies on document clustering. In this article we examine the most important concepts related to document clustering. Besides the algorithms we present comprehensive discussion about representation of documents, calculation of similarity between documents and evaluation of clusters quality.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 3; 271-277
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terms of trade i wzrost gospodarczy w Polsce w okresie 1980–2009
Autorzy:
Misztal, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/1810732.pdf
Data publikacji:
2012-09-30
Wydawca:
Uniwersytet Warszawski. Wydawnictwo Naukowe Wydziału Zarządzania
Tematy:
terms of trade
wzrost gospodarczy
model wektorowej autoregresji
economic growth
vector autoregressive model
Opis:
Celem artykułu jest analiza oddziaływania zmian cenowych terms of trade i zmienności terms of trade na wzrost gospodarczy w Polsce w okresie 19802009. Wyniki badań przeprowadzonych za pomocą modelu wektorowej autoregresji (VAR) ujawniły, że poprawa cenowych terms of trade w Polsce prowadził do wzrostu dynamiki PKB per capita, zaś wzrost zmienności cenowych terms of trade przyczyniać się do zmniejszenia tempa wzrostu PKB na mieszkająca w Polsce. Ponadto potwierdzono stosunkowo większe oddziaływanie zmian cenowych terms of trade niż zmienności terms of trade na dynamikę wzrostu gospodarczego w Polsce. Wykazano również, że zmiana cenowych terms of trade i zmienność terms of trade wyjaśniały w zbliżonym stopniu zmienność PKB per capita w Polsce w okresie 19802009.
This article aims to analyze the impact of changes in terms of trade and terms of trade volatility on economic growth in Poland in the period 19802009. The results of tests using the vector autoregressive model (VAR) revealed that improved terms of trade in Poland led to increased dynamics of GDP per capita, while the increase in terms of trade volatility reduced the growth rate of GDP per capita in Poland. In addition, there was confirmed the greater impact of changes in terms of trade, than the terms of trade volatility on the dynamics of economic growth in Poland. It was also demonstrated that the change in terms of trade and volatility of terms of trade, explained in a similar degree the variation of GDP per capita in Poland in the period 19802009.
Źródło:
Studia i Materiały; 2012, 1–2/2012 (14–15); 16-24
1733-9758
Pojawia się w:
Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ światowych cen ropy naftowej na ceny w Polsce
World oil price impact on prices in Poland
Autorzy:
Baranowski, Paweł
Sztaudynger, Jan Jacek
Powiązania:
https://bibliotekanauki.pl/articles/424758.pdf
Data publikacji:
2014
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
oil price
producer price
consumer price
Vector Error Correction Model
Opis:
The world oil price is an exogenous as well as key component and factor influencing domestic prices (especially transportation). The question is: how the oil price influences producer and consumer prices. We focus on a short- and long-term relationship between the domestic prices and oil price (expressed in Polish zloty). We use Vector Error Correction Models, with cost-based specification, i.e. including additionally wages and euro-zloty exchange rate. The degree of estimated long-term pass-through oil prices to producer and consumer prices is 0,15 and 0,05, respectively. Both producer and consumer prices have comparable size of short-term reaction to an oil price shock, but the producer price reaction is more prolonged.
Źródło:
Econometrics. Ekonometria. Advances in Applied Data Analytics; 2014, 2(44); 9-16
1507-3866
Pojawia się w:
Econometrics. Ekonometria. Advances in Applied Data Analytics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crude Oil Price and Speculative Activity: A Cointegration Analysis
Autorzy:
Socha, Robert
Wdowiński, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2076245.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
crude oil price
speculation
futures
cointegration
vector error correction model
Opis:
The aim of the study is to discuss the relationship of the crude oil price, speculative activity and fundamental factors. An empirical study was conducted with a VEC model. Two cointegrating vectors were identified. The first vector represents the speculative activity. We argue that the number of short noncommercial positions increases with the crude oil stock and price, decreases with the higher number of long non-commercial positions. A positive trend of crude oil prices may be a signal for traders outside the industry to invest in the oil market, especially as access to information could be limited for them. The second vector represents the crude oil price under the fundamental approach. The results support the hypothesis that the crude oil price is dependent on futures trading. The higher is a number of commercial long positions, the greater is the pressure on crude oil price to increase.
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2018, 3; 263-304
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the Cobb-Douglas Production Function as a Tool to Investigate the Impact of FDI Net Inflows on Gross Domestic Product Value in Poland in the Period 1994-2012
Autorzy:
Kosztowniak, Aneta
Powiązania:
https://bibliotekanauki.pl/articles/488854.pdf
Data publikacji:
2014
Wydawca:
Instytut Badań Gospodarczych
Tematy:
FDI
GDP
Cobb-Douglas production function
VECM (Vector Error Corection Model)
Opis:
The purpose of this paper is to analyse the impact of foreign direct investments net inflows on changes in GDP value in Poland in the period between 1994 and 2012 with the use of the Cobb-Douglas production function. The paper consist of five parts. Parts I and II present some aspects of the FDI influence on economic growth from the theoretical and empirical point of view. Part III defines conditions indispensable for the positive FDI impact on the economy of the host country. Part IV outlines changes of FDI flows in Poland in the period of 1994-2012. Part V includes the main assumptions of the Cobb-Douglas production function and an estimate of changes in GDP value for Poland in the period 1994–2012 with the use of the VECM. The factors significant for economic growth are also identified, including the significance of the net FDI inflows. Eventually, the effect of gross fixed capital formation, employment, FDI net inflows, exports and R&D on changes in the GDP value are determined.
Źródło:
Oeconomia Copernicana; 2014, 5, 4; 169-190
2083-1277
Pojawia się w:
Oeconomia Copernicana
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A price transmission analysis of pasteurised liquid milk in South Africa: granger causility approach
Autorzy:
Ramoshaba, Tshegofatso
Belete, Abanet
Hlongwane, Johanes Jan
Powiązania:
https://bibliotekanauki.pl/articles/1902627.pdf
Data publikacji:
2019-12-28
Wydawca:
Uniwersytet Przyrodniczy w Poznaniu. Wydawnictwo Uczelniane
Tematy:
price transmission
Granger causality
pasteurized liquid milk
Vector Error Correction model
Opis:
Price transmission studies have become increasingly important in Sub-Saharan Africa over the past decades because of its nature of providing clear and insightful information into these markets. In this study, the price transmission mechanism is described with an agricultural product within the dairy industry, namely pasteurized liquid milk. The aim of this study was to investigate and analyze the nature of the price transmission mechanism for pasteurized liquid milk in South Africa. The study used secondary time series data that covered a sample size of 17 years (2000–2016) for pasteurized liquid milk. The Granger causality test and the Vector Error Correction Model were used for data analysis. The Granger causality tests suggest that a bidirectional causal relationship exists between processor and farmgate prices, and also between retail and processor prices. On the other hand, retail prices were found to have a unidirectional causality effect on farmgate prices. The VECM results showed asymmetric price transmission, implying that retailers and processors react quicker to a price increase than to a price decrease. A price monitoring policy is suggested to be put in place in order to protect the consumers from unfair prices passed on by the retailers.
Źródło:
Journal of Agribusiness and Rural Development; 2019, 54, 4; 345-353
1899-5241
Pojawia się w:
Journal of Agribusiness and Rural Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prognozowanie inflacji w Polsce na podstawie modeli autoregresji wektorowej
Forecasting Inflation in Poland Based on Vector Autoregressive Models
Projections relatives à l’inflation en Pologne sur la base des modèles autorégressifs vectoriels
Прогнозирование инфляции в Польше на основе модели векторной авторегрессии
Autorzy:
Wójcik, Szymon
Powiązania:
https://bibliotekanauki.pl/articles/543416.pdf
Data publikacji:
2015-01
Wydawca:
Główny Urząd Statystyczny
Tematy:
Model wektorowej autoregresji
Prognozowanie
Inflacja
Zmienność poziomu cen
Vector Autoregression Model (VAR)
Forecasting
Inflation
Price level variability
Opis:
В статье были использованы модели векторной авторегрессии для прогнозирования месячного показателя потребительских цен в Польше. Выбор используемых макроэкономических переменных соответствовал трем теориям формирования инфляции: монетаристской, кейнсианской (курсовой) и издержек. В прогнозировании была использована концепция вне выборки (out-of-sample), а качество результатов было обследовано с использованием ошибок прогноз ex post.
W artykule wykorzystano modele wektorowej autoregresji do prognozowania miesięcznego indeksu cen konsumenta w Polsce. Dobór użytych zmiennych makroekonomicznych odpowiadał trzem teoriom powstawania inflacji: monetarystycznej, keynesowskiej i kosztowej. W prognozowaniu wykorzystano koncepcję prognozowania poza próbę (out-of-sample), a jakość wyników zbadano przy pomocy błędów prognoz ex post.
The article presents a usage of vector autoregressive models in forecasting polish consumer price index. Macroeconomic variables used in this paper are considered to reflect particular economic theories describing causes of inflation. Out-of-sample methodology was used in forecasting process. Accuracy of results was diagnosed by using ex post forecasting errors.
Źródło:
Wiadomości Statystyczne. The Polish Statistician; 2015, 1; 28-41
0043-518X
Pojawia się w:
Wiadomości Statystyczne. The Polish Statistician
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model monetarny kursu równowagi złoty/euro: analiza kointegracyjna
The Monetary Model of the Zloty-Euro Equilibrium Exchange Rate: Cointegration Analysis
Autorzy:
Wdowiński, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/574303.pdf
Data publikacji:
2011-03-31
Wydawca:
Szkoła Główna Handlowa w Warszawie. Kolegium Analiz Ekonomicznych
Tematy:
Frankel monetary model
zloty/euro equilibrium exchange rate
cointegration analysis
vector error correction model
Opis:
The author carries out a cointegration analysis for the nominal exchange rate of the zloty against the euro according to a monetary theory developed by U.S. economist Jeffrey A. Frankel (1979). Wdowiński estimates a cointegration vector for the period 1999M7-2008M9. Long-term estimates show that the euro exchange rate depends on changes in industrial production and on short- and long-term interest rates, the author says. The influence of M1 money supply proves to be statistically insignificant. The departure of the euro rate from a state of monetary equilibrium was corrected slowly, the author says, because the half-life of the divergence was almost two years. The solution of the model showed that the euro exchange rate diverged significantly from a state of equilibrium determined by fundamental factors in the 1999M7-2004M1 period, while showing smaller deviations in the 2004M2-2008M9 period. Overall, the author observed periods when the zloty was both overvalued and undervalued against the euro due to a long-term equilibrium rate. The deviations stabilized noticeably from May 2003. In the 2003M5-2006M3 period, the zloty was overvalued by 9.6% on average, while in the 2006M4-2008M9 period it was undervalued by 9.3%. In the short term, the zloty tended to appreciate as a result of increases in short-term interest rates. According to the author, fundamental economic factors in Poland and the euro area point to the existence of a trend whereby the zloty is gaining ground against the euro, while short-term changes in this rate may be significant due to a growing macroeconomic risk.
Źródło:
Gospodarka Narodowa. The Polish Journal of Economics; 2011, 246, 3; 67-86
2300-5238
Pojawia się w:
Gospodarka Narodowa. The Polish Journal of Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Portfolio management of a small RES utility with a structural vector autoregressive model of electricity markets in Germany
Autorzy:
Maciejowska, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2204084.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
intraday electricity market
day-ahead electricity market
structural vector autoregressive model
probabilistic forecasting
trading strategy
Opis:
Electricity producers and traders are exposed to various risks, among which price and volume risk play very important roles. This research considers portfolio-building strategies that enable the proportion of electricity traded in different electricity markets (day-ahead and intraday) to be chosen dynamically. Two types of approaches are considered: a simple strategy, which assumes that these proportions are fixed, and a data-driven strategy, in which the ratios fluctuate. To explore the market information, a structural vector autoregressive model is applied, which allows one to estimate the relationship between the variables of interest and simulate their future distribution. The approach is evaluated using data from the electricity market in Germany. The outcomes indicate that data-driven strategies increase revenue and reduce trading risk. These financial gains may encourage energy traders to apply advanced statistical methods in their portfolio-building process.
Źródło:
Operations Research and Decisions; 2022, 32, 4; 75--90
2081-8858
2391-6060
Pojawia się w:
Operations Research and Decisions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the vector-autoregression VAR model in the analysis of unemployment hysteresis in the context of Okun’s Law
Autorzy:
Kołbyko, Patryk
Powiązania:
https://bibliotekanauki.pl/articles/2207120.pdf
Data publikacji:
2023-02-22
Wydawca:
Uniwersytet Ekonomiczny w Poznaniu
Tematy:
vector-autoregression model VAR
time series analysis
hysteresis in the labour market
Okun’s Law
macroeconometrics
Opis:
Unemployment is an important macroeconomic issue both in theoretical terms and for economic reality. On the theoretical ground, the unemployment rate, which is a measure of the share of unemployed units of the labour supply in the economy, determines the output gap at a certain adjustment parameter determined by the marginal productivity of labour. One of the causes of rising or persistent unemployment in the economy is the phenomenon of unemployment hysteresis, which occurs as a result of changes in the marginal disutility of labour, the strength of the wage bargain and other exogenous conditions arising in previous periods. The purpose of the study conducted in the following paper is to investigate the phenomenon of hysteresis in the labour market by analysing the significance of the impact of the unemployment rate in previous periods. In addition, the work aims to study Okun’s Law as an effect of production dynamics on the unemployment rate. The study of the dependence was carried out through the estimation of a macroeconometric time series model—vector-autoregression (VAR) on the example of statistical data for Poland obtained from Statistics Poland (Stat.gov.pl) and complied raports about national accounts in the quarterly sequence for the years 2015–2021. The period of the study was arbitrarily selected with the observation of business cycle fluctuations in the above time frame. Empirical analysis of selected structural parameters through estimation of the vector-autore- gression model showed a significant influence of the time series in the formation of the unemployment rate, which confirms the influence of the analysed phenomenon of hysteresis in the labour market. In addition, the vector-autoregression model for inter- val forecasting through the use of dynamic prediction proved to be a posteriori accurate forecasting model of the unemployment rate in the Polish economy.
Źródło:
Research Papers in Economics and Finance; 2022, 6, 2; 68-85
2543-6430
Pojawia się w:
Research Papers in Economics and Finance
Dostawca treści:
Biblioteka Nauki
Artykuł
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