BADANIE PUNKTÓW ZWROTNYCH CEN ROPY NAFTOWEJ W LATACH 2015 - 2019

This paper aimed at identification of turning points in prices of crude oil from 2015 to 2019 through application of Perron test. It also attempted to detect geopolitical events that could have caused these changes in trend structure. This part of research was based on oil market analysts’ comments and on market reports available at professional business websites. The research brings to conclusion that problems related to the oversupply of crude oil in the United States affected its prices the most. Reports informing about the increasing number of oil platforms working in North America and low demand in the fuel market often induced long-term price reductions at NYMEX and ICE.

SIMULATION OF PARTICLE SWARM OPTIMIZATION FOR INVESTMENTS ON STOCK MARKET

This work reports simulations performed using Particle Swarm Optimization (PSO) as applied to investments on the stock market. About 480 stocks belonging to the S&P500 index have been taken into account. A naive approach has been developed in which one simulation step corresponded to one trading period. As a second ingredient of the investment strategy, the relative strength of an asset has been employed. The results are analyzed with respect to the parameters of PSO.

WIZUALIZACJA JAKO NARZĘDZIE WSPOMAGAJĄCE ANALIZĘ DANYCH W PROCESIE DYDAKTYCZNYM

Presentation of information in a graphical form is one of the basic forms of data presentation. It is a great support during both the preliminary and further analysis. However, an incorrect graphical form can lead to misinterpretation and, in consequence, to erroneous conclusions. This paper presents some examples of graphical data visualisation that come from authors’ teaching experience. The article includes cases of both correct and incorrect data presentation.

WSKAŹNIKI DOBROBYTU O CHARAKTERZE ODSETKÓW - PRZEGLĄD

This article is revision-based. The aim of the research was to define the welfare measures used, which are in the form of proportion. At the beginning, a historical sketch of the welfare economy was presented. Then, the welfare domains described in the literature are presented and the corresponding welfare indicators were identified. In the next section of the article indicators classified into particular subgroups were presented. The subgroups are: traditional measures of the economy, modified national accounts, index measures and environmental indicators. The article ends with a discussion of the data sources for the welfare indicators and based on that the indicators in the form of proportion were indicated.

O PROBLEMACH STOSOWALNOŚCI MIERNIKÓW SYNTETYCZNYCH DO PORZĄDKOWANIA OBIEKTÓW

The problem of building a stable synthetic index used to organize the objects described with multiple partial indexes has been and is the subject of the authors' considerations. In our research, we aimed at the construction of a measure that would be insensitive to the input data, the results that would not depend on the method of normalization of the variables, the choice of the distance measure (similarity) and the selection of features. Our experience is consistent with the results of the work of the outstanding American statistician L. Breiman. A single classifier (synthetic measure) may be far from optimal, while combinations of many result in a classifier that is close to optimal and stable. Unfortunately, when "weak" classifiers are used, the combination may result in an even worse classifier. In the work, we presented the consequences of choosing a synthetic indicator for organizing objects described by many features on a practical example of farms in the EU countries covered by the FADN survey.

NIEPEWNOŚĆ NAUKI A DZIAŁANIE, CZYLI – PROBLEMY Z EVIDENCE – BASED POLICY

The purpose of this article is primarily to introduce the topic of scientific uncertainty to the wider context of economics and management. Scientific uncertainty is one of the manifestations of irreducible uncertainty and reflection on it should enable better decision making. An entity that bases its operation on current scientific research, which depreciates over time and ultimately leads to erroneous decisions, is referred to as the “loser”. The text indicates estimation of potential scale of this problem supplemented by an outline of sociological difficulties identified in the analysis of the process of building scientific statements. The article ends with a sketch of the answer to the question “how to act in the context of scientific uncertainty?”.

ANALIZA DEBIUTÓW NA RYNKU GŁÓWNYM GPW W LATACH 2005-2019

This study deals with debuts on the WSE Main Market in 2005-2019. In this context, information on the subject of the debut as well as the related procedural and organizational requirements were referred to at the beginning. The following section presents an overview of the data available on the WSE websites relating to the problem area under study, and an analysis of selected quantitative statistics on their basis. An important part was devoted to examining the scenarios of price changes on the first trading day and carrying out statistical application based on them.

ANALIZA PORÓWNAWCZA STANU SŁUŻBY ZDROWIA W WOJEWÓDZTWACH

The article compares the state of health care in selected thematic areas in voivodeships. It focuses on 2 main aspects, such as: health care expenses and the number of specialists. The analysis was carried out on data from 2018-2019. Its aim was to group voivodships according to selected variables regarding the state of health care. Their geographical location and demography were analyzed. The difference between the state of health care in urban and rural areas was featured.

IDENTYFIKACJA CZYNNIKÓW WPŁYWAJĄCYCH NA OCENĘ RYZYKA KREDYTOWEGO MIKROPRZEDSIĘBIORSTW DZIAŁAJĄCYCH W REGIONIE ŁÓDZKIM

Microenterprises have limited sources of external financing that is provided mostly by banks. The aim of our research is to identify factors influencing credit risk evaluation of small firms. Investigation is provided applying linear regression using real data concerning microenterprises functioning in Lodz region which obtained different form of credits in years 2016-2018. The results show that earnings and years of operating on the market are the most important factors which affect the improvement of credibility.

SPOŻYCIE OWOCÓW W POLSCE – ANALIZA NA PODSTAWIE JEDNORÓWNANIOWYCH NIELINIOWYCH MODELI EKONOMETRYCZNYCH

The article dealt with an assessment of the fit of typical non-linear demand models for fruit. The power function, the exponential function with the inverse and the Törnquist function for the basic goods were used in the econometric analysis. The models were estimated on the basis of income quintile groups’ data published by the Central Statistical Office. Based on the estimated model parameters, income elasticities of demand were calculated. It was found that the models described by the power function and the Törnquist function for basic goods were characterized by a better goodness of fit than the models using the exponential function with the inverse.