We study to what degree and how homophily and network properties affect individual citation counts of researchers in the sociology departments of three East European countries, namely Poland, Romania, and Slovenia. We built first-order personal coauthorship networks out of the Web of Science publication records. Each sociologist is assigned as a focal node or ego, while her coauthors are alters. We analyze the data using structural measurements methods, hierarchical regression models, and we make visualizations based on the clustered graph technique. For all three populations, our results indicate that the mean score of the citations of alters substantially predicts the citation counts of egos. In particular, citation similarity increases the chances for coauthorship ties. Evidence for the impact of network properties on the citation levels of egos is mixed. For Poland, normalized ego-betweenness shows a negative effect on citation counts, while network density displays a positive one. For Romania and Slovenia, network characteristics have only a minor impact. Even if the visual summarization of the personal networks uncovers a wide palette of coauthorship patterns, homophily appears to be pervasive. These results are relevant for domestic policy makers who aim to improve the aggregated research performance in East European countries. Modern social network analysis, generally, builds on the assumption that network patterns have significant consequences for the embedded actors 1 . Actors' outcomes (both benefits and disadvantages) and future characteristics are heavily affected, not only by the actor's own attributes, but also by the structural properties of their network positions 2 . During the last decades, social network analysis has become extremely popular, being applied in a variety of disciplines, such as social sciences, physics, epidemiology, biology 3 , informetrics 4 , scientometrics 5 and bibliometrics 6 . The application of social network analysis to the study of coauthorship activity 7-12 has proved to be extremely fruitful in understanding coauthorship tie creation, the diffusion of innovation, the academic success and career longevity, the creation of prestige, the increase of visibility, the intellectual structure in science, the existence of research fronts etc. Commonly, at an individual level of analysis, coauthorship data have been used as inputs to build up coauthorship (collaboration) networks, in the form of either whole-networks 7, 10, [13] [14] [15] [16] , or in the form of personal networks (ego-neworks) [17] [18] [19] [20] . Ego-networks (personal networks) are made up of an ego (the focal actor), ego's alters (actors ego has specific social relations with), the relationships among alters (alter-alter ties) and between ego and alters 21 . Personal network analysis focuses on the effects of social context (depicted as a specific pattern of ties) on individual characteristics, studying the social relations of individuals 22 . Generally, within personal network studies, two classes of variables have received closer attention: network composition variables (characteristics of the ego, of the alters, of ego-alter relationships, as well as of the alter-alter ties) and network structure variables (centrality measures such as degree, betweenness, closeness; aggregate variables such as density, core/periphery, number of components and of isolates, dyads, triads, efficiency, constraint etc.) [23] [24] [25] [26] . Personal networks have been of great interest in the study of various topics, such as: social support 27 , social protection 28 , health 29 , social capital 23, 30 , searching a job 31 , migration 26,32 etc. Interestingly, the studies employing a personal network analysis framework for the study of coauthorship are still scattered and sparse. A few studies stand up, reporting markedly contradictory results. For instance, it was investigated how scholarly performance
REF studied how different network properties affect citation counts of sociologists of East European countries including Slovenia.
Homophily in coauthorship networks of East European sociologists
Scientific Reports
Scientific Reports
Sociology Medicine