Диссертация (1136614), страница 15
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We are able to understand the underlying dynamics of grades and networks witha simple model. The lack of a social pull effect in classical educational settings could haveimportant implications for the understanding of the observed persistence of segregation,inequality and social immobility in societies.IntroductionHomophily is the tendency of humans to associate with others who share similar traits.
It hasbeen observed for a multitude of different traits, including gender [1, 2], race [1–3], academicachievements [2, 4, 5], genotypes [6], aggression [7], obesity [8], happiness [9], divorce [10],smoking [11], or sexual orientation [12]. Homophily is found for different types of relationships such as between spouses [13], friends [14] and co-workers [15], and occurs in a widerange of environments including kindergarten [16], large human gatherings [17], Wall StreetPLOS ONE | https://doi.org/10.1371/journal.pone.0183473 August 30, 20171 / 16Formation of homophily in academic performance[18], populations of hunter-gatherers [19], or virtual societies of online gamers [20, 21].Homophily is considered as one of the fundamental organizational principles of human societies [22], and has a number of important social implications such as the origin of segregation[23] or the perpetuation of economic inequality and social immobility [24].Even though there exists an extensive body of research on homophily, it remains a challenging question to understand its origins and how it forms and develops over time.
For traits thatcan not be changed, such as race or gender, homophily arises through a re-structuring processof inter-human relationships, where on average links between people with similar traits arecreated, while links between dissimilar people are dissolved. If traits can be changed over time,the situation becomes more involved.
In this case, there exist two mechanisms to explain theformation of homophily from an initially homogeneous population: socialization and socialselection [25]. The mechanism of socialization means that people change their traits to increasesimilarity to those they are connected to in a static social environment (network).
This is schematically shown in Fig 1(a). This mechanism is sometimes also referred to as ‘social contagion’or ‘peer influence’. Under the mechanism of social selection, individuals re-arrange their socialties so that they become linked to people that are similar in traits, see Fig 1(b). If both mechanisms are at work at the same time, traits and social networks are said to co-evolve. The literature on the aspect of co-evolution is limited because of the lack of the simultaneous availabilityof longitudinal social networks and traits data.In this paper we focus on homophily in academic achievements.
It might be expected thatacademic performance plays an important role in friendship sorting. Homophily in achievements may arise from several factors, including school organization [26] and school policiessuch as ability-grouping [27] that increases the probability to meet students with similar academic performance.
However, such policies are not common in the Russian education systemthat is characterized by its egalitarian nature and its high level of standardization. There is notracking or ability-grouping in the particular school we use in this study. Students from thatschool are from the same neighborhood, the majority of them lives within 10 minutes walkfrom the school (see S1 Text).Adolescence is the period of major social changes in the lives of young people [28].
Many ofthese changes lie in the area of peer relationships [29]. Starting from early adolescence youngpeople become much less involved with their parents and more with their peers [30]. In thisperiod, adolescents are concerned about their popularity among friends and seek peer acceptance [31]. To no surprise, peer influence extends to many areas of their life, including academic [32].
It was previously shown that peers may influence school engagement [33],disruptive behaviour in the classroom [34], and academic performance [35].However, similarities between friends are not simply explained by peer influence. Adolescents also choose friends with similar behaviours and attitudes [36]. One major feature of adolescence is formation of a personal identity [37], it means that young people begin to exploreand examine psychological characteristics of the self in order to discover who they really are,and how they fit in the social world in which they live [38].
Peer-group membership is also apart of identity as the group of friends to which adolescents belong helps define who they are[39]. We might expect, for example, that high performing students seek friendship with otherhigh performing students as part of their academic identity formation.
There is evidence thatthe importance of pears peaks in the early adolescence and then gradually declines whenyoung people develop a mature sense of autonomy [31].Homophily in academic performance has been studied with network data collected withquestionnaire-based surveys [4, 5]. The design of these studies makes it hard to follow the temporal evolution of social networks. The availability of new technologies and big datasets provides researchers with novel tools to observe the dynamics of social networks with highPLOS ONE | https://doi.org/10.1371/journal.pone.0183473 August 30, 20172 / 16Formation of homophily in academic performanceFig 1. Two basic mechanisms to understand the origin of homophily. Nodes represent individuals, different colors indicatedifferent traits.
Links correspond to social ties, e.g. friendship. Increase of similarity between connected individuals may either arisefrom changes in traits (socialization process) (a), where individuals change their trait according to the dominance of that trait in theirlocal social networks, or through re-wiring of their local social networks (social selection process) (b), where individuals re-shape theirsocial contacts such that their trait matches those in the new environment better.https://doi.org/10.1371/journal.pone.0183473.g001PLOS ONE | https://doi.org/10.1371/journal.pone.0183473 August 30, 20173 / 16Formation of homophily in academic performancetemporal precision.
For example, the temporal structure of social networks has been reconstructed by email data [40], computer game logs [41], or interactions on learning managementsystem platforms [42].The quantification of social ties remains a challenging task [43]. Even traditionalapproaches that are based on self-reported friendship ties may contradict the common definition of friendship.
For example, it was shown that only half of self-reported friendship linkswas reciprocal (despite the fact that almost all of them were perceived as reciprocal) [44]. Alternatively, friendship links may be inferred from digital records of human behaviour, allowingto track the detailed evolution of social ties [45], including those among high school students[46]. We approximate friendship links between students from their activities on the social networks site, in particular from the placement of “likes” on other students’ pages.
Some classicalsociological theory suggests that social relationships are maintained through the symbolicexchanges [47], where exchange of “likes” may be considered as such a “symbolic ritual” [48].Indeed, there is direct empirical evidence that “likes” correlate with real friendship ties [49].In this paper, we use a unique anonymized dataset to observe the temporal formation ofacademic homophily based on social interactions between Russian students from a public highschool and a university.
The dataset contains information on the students’ academic performance at several time points during their studies together with the detailed information aboutthe evolution of their friendship networks (see S1 Text). These networks between studentswere obtained from the largest European social network site VK (http://vk.com), that providesa functionality similar to Facebook. VK users create their profiles with information about theiridentity, education, interests, etc. The use of the real name is required by VK.
Users may indicate other users as their friends. VK friendship is mutual and requires confirmation. However,using VK friendship links is not the most efficient way to study the dynamical evolution ofactual friendships, since only information about the current friendship is available, whichmakes it practically impossible to extract the dynamics of VK friendship links. It is also impossible to distinguish active friendship ties from obsolete ones since VK friendship links arerarely dissolved. We, therefore, approximate friendship links between students from the placement of “likes” on other students’ pages. A link from one student to another is created if a“like” was placed at least once within a given period of time (see S1 Text).
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