Построение модели выбытия студентов по данным университетов с разной периодичностью рубежного контроля
Pooling the data from a number of universities into a single sample poses a problem for researchers who are performing regression analysis of student attrition. Academic year can be divided into different academic terms in different universities, and this discrepancy has to be taken into account. This paper considers a problem of using data with different periodicity in the framework of discrete-time event history analysis and gives an example of an estimated attrition model.
Russia has been characterized by an early and universal marriage for a long time. After the Soviet Union collapse, the average ages for marriage have been rising, marital unions have becoming rarer while cohabitations have becoming common because of changes in norms and values that citizens of many other countries witnessed several decades before. Many scholars have observed this trend and tried to explain its reasons through the perspective of the Second Demographic Transition and Globalization theories. Current research is another attempt to understand these changes. The aim of this research was to define the nature of cohabitations in Russia, and find out the factors of entrance to non-marital unions. For these purposes, we used Event History Analysis and Sequence Analysis. The key requirement in using these methods is applying longitudinal or retrospective collections of data that have become the gold standard of current quantitative social science. Accordingly, the three-wave panel data of the Russian part of “Generations and Gender Survey” and the retrospective data of “Person, Family, Society” were chosen for this study. The opposite trends of matrimonial behavior were revealed: the younger Russian people are, the higher their probabilities to start the first cohabitation and the lower their risks to have the first marriage. Cohabitation is not a complete alternative to marriage in our country yet, but the proportion of Russians, for whom cohabitation does not grow into a marriage, rises, and young people start to consider a non-marital union appropriate for childbearing. It is a sign that cohabitation is close to become an independent social institution for young non-religious people who get secondary vocational education in big cities.
Student withdrawal (attrition) is becoming an actual phenomenon due to demographic changes, modernization of the economy and education, especially for universities located in economically depressed areas. The tradition of research on student withdrawal is still being formed in Russia, so it is important to clarify the main terminology used for the analysis of withdrawal, to develop a theoretical framework that takes into account the specifics of Russian universities, and to specify the prospects for the elaboration of research. A review of the terminology used in international studies to study the withdrawal as well as the history of studying this phenomenon in the USA is presented. The basic concepts of withdrawal, developed in sociology, psychology, organization theory and economics, are considered. They indicate the effectiveness of accounting for a wide range of factors of differing natures in the study of withdrawal: the processes of social and academic integration, the psychological characteristics of students, the organizational characteristics of the university and educational programs. When adapting existing models to Russian higher education, it is important to take into account that compulsory withdrawal caused by academic failure of students predominates in Russian universities, while international models were created to describe voluntary withdrawal from higher education institutions. National research which can serve as the basis for the development of a model of student withdrawal from Russian universities is analyzed.
A model for organizing cargo transportation between two node stations connected by a railway line which contains a certain number of intermediate stations is considered. The movement of cargo is in one direction. Such a situation may occur, for example, if one of the node stations is located in a region which produce raw material for manufacturing industry located in another region, and there is another node station. The organization of freight traﬃc is performed by means of a number of technologies. These technologies determine the rules for taking on cargo at the initial node station, the rules of interaction between neighboring stations, as well as the rule of distribution of cargo to the ﬁnal node stations. The process of cargo transportation is followed by the set rule of control. For such a model, one must determine possible modes of cargo transportation and describe their properties. This model is described by a ﬁnite-dimensional system of diﬀerential equations with nonlocal linear restrictions. The class of the solution satisfying nonlocal linear restrictions is extremely narrow. It results in the need for the “correct” extension of solutions of a system of diﬀerential equations to a class of quasi-solutions having the distinctive feature of gaps in a countable number of points. It was possible numerically using the Runge–Kutta method of the fourth order to build these quasi-solutions and determine their rate of growth. Let us note that in the technical plan the main complexity consisted in obtaining quasi-solutions satisfying the nonlocal linear restrictions. Furthermore, we investigated the dependence of quasi-solutions and, in particular, sizes of gaps (jumps) of solutions on a number of parameters of the model characterizing a rule of control, technologies for transportation of cargo and intensity of giving of cargo on a node station.