The 65th issue of The Works and Materials of the Research Institute of Economic Development contains a selection of major works of the author accomplished within the framework of the Research Program of the Committee for Scientific Research no 1 H02C 003 14 "Research methods on Poland's economic performance with composite business indicators" in the years 1998- 1999. Other works by the members of the Research Team accomplishing the project were published in some previous issues The Works and Materials of RIED, in the series of Papers on Poland's economic performance, in the series of Monographs and Works of the Warsaw School of Economics and in other collective works. Under this research project a lot of works were also prepared in a form of interventions in domestic scientific seminars, domestic and foreign conferences, the Cl RET Congress as well as in a form of articles published in domestic and foreign scientific periodicals, dealing with the business research. In this book the implementation of some research methods on economic performance with composite business indicators has been presented. The methods well-known in the literaturę of the subject have been chosen, implemented rarely or for the first time, using qualitative indicators of economic activity as well as methods the author had proposed in his earlier works. The book consists of four chapters. The method of research on structures of economic aggregates, proposed in Chapter I, is based on business surveys' results. The method was described and illustrated by the output of the industrial sector. The method is characterized by the existence of the quantitative link between a certain portion of the output (in para. 1.1 this is a production for export, in para. 1.2 this is a production which has not been currently sold) and consumer's type of output, procurement type of output and investment type of output. Having this link (for instance in a form of equation) one may evaluate which parts of the above three types are assigned for export (para. 1.1) or are difficult to sell (para. 1.2) as well as how total production for export or unsold output are distributed among the three particular types of industrial products. In Chapter II some possibilities of making economic outlook with selected business indicators have been presented. In sub- Charter 2.1 the possibility of making the industrial production outlook on the basis of demand of this sector consumers' is being studied. It is checked whether the output adjusts itself to demand ( domestic and foreign) and examined if these adjustments are quicker in relation to the domestic or foreign demand, in private or public sector of the industry, how big current ranges of adjustments are, as well as whether on the basis of changes in demand the outlook for industrial output changes can be madę. The implemented method is focused on making the outlook on the basis of equations describing the current changes in output with variables being interpreted as domestic and foreign demand declared currently and in the previous periods. The equations are the basis for making the outlook for changes in industrial output on the basis on the changes in demand. In sub-Chapter 2.2 the outlook for GNP growth ratę in the second half of 1998 has been presented. The research presented in this sub-Chapter is mainly of methodological naturę. The results obtained show a direction of futurę studies concerning consistency of the quantitative description of the GNP growth ratę with the business barometer. A substantial current barrier is a too short time series of the business barometer which only allows to demonstrate a method of making the outlook for the GNP growth ratę. The method is based on existing linear interdependency between the GNP growth ratę series and the monthly one corresponding to the value of linear- oscillatory function of the business barometer with a total value of temporal variable. In sub-Chapter 2.3 an attempt to make the outlook for a very business barometer has been undertaken whose temporal course corresponds to the growing stream of the GNP. The aim of this study is to presents the business barometer outlook for the Polish economy for the years 1999-2000. The barometer temporal series in the Research Institute of Economic Development version has been assumed in the research for fuli years from 1993 to 1998. The series is 72 (months) long. The business barometer outlook has been based on the linear trend-free- 12-month- mobile average values of the barometer,. The research has shown that the average satisfies a reflexive equation after a two-series delay. Using this result a current mobile average value of the barometer may be subordinated to the previous values of the average. Sub-Chapter III begins with an analysis of economic cycles with stationary differential equations i.e. such in which aggregated variables correspond to different periods. In this part also the foundations of harmonie analysis have been treated. In the second part of this chapter cyclical economic changes in the temporal course of the business barometer for the Polish economy have been presented. In the sub-Chapter 3.3 the correctness of conclusions concerning the economic cycles discovered with differential analysis has been examined, the ranges of both the cycles and seasonal fluctuations have been calculated. The method of harmonie analysis has been used which can be used for the cycles being a complete multiple of 12 months. The method of differential analysis, implemented in sub-Chapter 3.2 does not allow to evaluate an average rangę of cyclical fluctuations because this method usually results in monotonically variable ranges, and above this, a phenomenon of cyclical waves interference is very likely to appear in the temporal course of the mobile average of the business barometer. The phenomenon is demonstrated by the interference of local maximal and minimal values in the temporal course of the barometer's mobile average in some months. This makes it impossible to determine by the method of differential analysis which part of the fluctuations rangę is of seasonal naturę and which is caused by oscillations coming from other factors. In Chapter IV some aspects of the development of industrial sector of the Polish economy have been researched with the qualitative indicators. In the first part of this chapter the Solow's method has been implemented to research the effects of technological progress in the public, private and entire industry. In this connection qualitative indicators- the balances of changes in the industrial output have been used. In the second part of Chapter IV a methodological aspect of composite business indicator's construction for the entire industry is being treated. In the study the proportions in which both private and public sectors of industry contribute to total output sold of the Polish industry.