The paper focuses on the internal validity of clustering solutions. The "goodness" of a cluster structure can be judged by means of different cluster quality coefficient (QC) measures, such as the percentage of explained variance, the point-biserial correlation, the Silhouette coefficient, etc. The paper presents the most commonly used QCs occurring in well-known statistical program packages, and we have strived to make the presentation as non technical as possible to make it accessible to the applied researcher. The focus is on QCs useful in person-oriented research. Based on simulated data with independent variables, the paper shows that QCs can be strongly influenced by the number of clusters and the number of input variables, and that the value of a QC can be fairly high even in the absence of any real cluster structure. When evaluating the internal validity, it is helpful to relate the QCs of a clustering solution to those obtained in parallel analyses of random data. We also introduce a new type of QC, measuring the relative improvement (MORI) of a QC obtained for a certain clustering solution relative to the corresponding QC based on a relevant type of random data.

This study aims to review and summarize national and international literature that seeks to determine what quality education actually is, as well as look at what is happening as regards students" achievements. The current study aims to carry out a literature review with the purpose of laying down the foundations of future empirical research related to student achievement and educational effectiveness. This literature review indicates relevant results and comes to conclusions regarding analyses and research in the topic of student achievement. First, the study briefly introduces the connections between quality, effectiveness and equity; then it reveals the context of student achievement at schools; and, finally, it looks at the most important factors determining student and school achievement. The results of this literature review will support the conceptualisation and operationalisation of a future empirical examination of student achievement.

Attrition is an important issue in higher education, especially in the field of computer science (CS). Here, we investigate to what extent an education reform affects the attrition of students by analyzing the pattern of grades of CS students’ academic achievement from 2010 to 2018 by IRT, based on Rasch-model analysis. We analyze data from 3673 undergraduate students of a large public university. In 2016 an education reform—as an intervention—was added to our BSc program: all theoretical lectures became compulsory to attend and we introduced a learning methodology course for all first-year students. According to our results, after the education reform most subjects became accomplishable, and students with lower levels of ability also tried to take exams. We succeeded in retaining 28% of our students. Analyzing students’ results could help administrators develop new programs in order to increase retention.

Each human group and each society is a complex system of cooperative and competitive relationships. These two relations are intertwined, however, it is not indifferent in what way and to what extent. The present research has aimed at revealing the requirements of cooperative competition which is a competitive process with a high degree of cooperation among the competing parties. The Critical Incident Technique was applied. This procedure is based on the direct observation of human behaviour and was elaborated in order to examine complex interpersonal phenomena and to provide ecological validity. Altogether 483 critical incidents were described by teachers and university students of education. They were instructed to recall competitive relationships that have certain characteristics (e.g. high degree of cooperation among the parties vs no cooperation among the parties; high degree of trust among the parties vs high degree of distrust among the parties, etc.) After the free description of the incident, the participants had to characterize the competitive event along different dimensions on a Likert-scale, for instance intense/not intense competition; rules kept or violated. Applying principal component analysis, four different scales were constructed: the Cooperation Scale (i.e. the relationship among the competitors, cooperation, trust and communication), the Motivation Scale (i.e. motivation, the importance of the goal, development and learning), the Fairness Scale (i.e. rule keeping, no aggression and no manipulation) and the Enjoyment Scale (i.e. enjoyment and positive stress). The correlation analysis of the interrelations among the scales and individual variables has indicated that the high degree of cooperation among the competitors was positively related to fairness, the clarity of rules of competition, enjoyment and motivation. Less cooperation among the competitors was related to higher level stress and more intensive competition among them. If competitive processes are characterized by high degree of cooperation, i.e. they are cooperative competitions that have no detrimental but only beneficial effects, then they combine the constructive aspects of both cooperation and competition.

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