Sociologiska Institutionen

Masteruppsats i sociologi, 30 h.p.

Ht 2017

Handledare: Love Bohman

Homophily and friendship

dynamics

An analysis of friendship formation with respect to homophily

principle and distinctiveness theory

Author: Sepehr Saeidibonab

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Abstract

People always find themselves interacting with others and forming ties with them; these ties shape

an individual’s social network which help form the self-conception and identity of a person. In

discussing the essence of social networks and how they are formed the concept of homophily is of

high significance. Therefore, the purpose of this research is to show the association between

homophily and the process of friendship formation. As the structure of any social network is

important in tie formation, I have also intended to study homophilous tie formation from a

distinctiveness theory perspective, suggesting that individuals with minority characteristics are

more prone to form friendship ties with each other. The types of homophily studied in this research

are gender, religion, nationality/ethnicity, and political views. The data is gathered from the cohort

which started grade 10 in upper secondary education in a school in Stockholm in Autumn 2012.

The analyses were conducted using logistic regression. The results indicated the existence of

gender homophily and national homophily. However, religious homophily did not appear to have

a robust association; political homophily was only robust for individuals who were participating

in political meetings. However, due to lack of sufficient data, the relations between network

structure and homophilous relations could not be accurately tested. Since the data were not

collected randomly and the school was chosen due to its specific characteristics, it is not possible

to generalize the results of the research to all the adolescents living in Stockholm. However, this

research sheds some light on the mechanisms at play in friendship formation among adolescents.

Keywords

Homophily, Social network, Network structure, Distinctiveness theory

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Table of Contents

1 Introduction ............................................................................................................................. 1

2 Theory and previous research ................................................................................................. 3

2.1 Students and friendship dynamics .................................................................................... 3

2.2 Types of homophily ......................................................................................................... 4

2.2.1 Gender homophily .................................................................................................... 5

2.2.2 Religious homophily ................................................................................................. 6

2.2.3 Political homophily ................................................................................................... 7

2.2.4 National/ethnic homophily........................................................................................ 8

2.3 Homophily in social network ......................................................................................... 10

3 Research question ................................................................................................................. 12

4 Data ....................................................................................................................................... 12

4.1 Dependent & Independent variables .............................................................................. 13

5 Method of research ............................................................................................................... 16

6 Results ................................................................................................................................... 18

6.1 Gender homophily .......................................................................................................... 20

6.2 Religious homophily ...................................................................................................... 22

6.3 National/ethnic homophily ............................................................................................. 23

6.4 Political homophily ........................................................................................................ 25

6.5 Homophily and friendship .............................................................................................. 26

7 Discussion ............................................................................................................................. 28

8 Conclusion ............................................................................................................................ 32

9 References ............................................................................................................................. 33

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1 Introduction

While moving around through social spaces, people establish various relations which have

considerable effect on them; these relations or networks shape or even change their desires, beliefs

and opinions. In other words, individuals, almost constantly, find themselves interacting with

others and forming ties with them. These ties shape the individual’s self-concept and define his/her

identity, desires, beliefs and opinions (see: Edling & Rydgren, 2014; Hedström, 2005). Hence,

studying social networks can benefit us in better understanding the individuals’ behavior and future

actions which, ultimately, would lead to a more comprehensive grasp in how society works. People

get involved in various networks either due to individual characteristics, social contexts and/or

social opportunities; these social networks can be both intentional and unintentional.

Essentially, one of the main elements to consider in social network formation is proximity. That

is, people become friends with people who are geographically close to them. For instance, students

become friends with class mates, co-workers become friends with other co-workers, etc. Hence, a

focused social organization is important in network formation (see: Feld, 1981). However, in

discussing the essences of social networks and how they are formed or structured, in addition to

propinquity, the concept of homophily is of high significance; as is indicated in the old saying:

“birds of a feather flock together”. Homophily principle indicates that people tend to socialize with

similar others. That is, others who share some characteristics with the individuals. These

characteristics can include age, religion, ethnicity, nationality, opinion and values, etc.

(McPherson, Smith-Lovin, & Cook, 2001).

In recent years, societies have become more and more diverse and multicultural due to

globalization and the dramatic increase in migration (Van Der Wildt, Van Avermaet, & Van

Houtte, 2015). This event produces a huge opportunity for individuals to make acquaintance with

people from other cultures and exchange information and ideas with people from all around the

globe. However, this idea is not penetrated in most social networks and people still prefer

homophilous relations (Smith, Van Tubergen, Maas, & McFarland, 2016).

Individuals, in general, prefer homophilous relations for various reasons. For instance, people

usually prefer to be friends with others of the same religion. This can be due to the fact that having

the same religious belief generates trust among two individuals and also they share the same

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opinion regarding the concept of “good people” (Windzio & Wingens, 2014); further, with regards

to national or ethnic homophily, it is argued that the issue of rational choice drives people to choose

friends from the same national or ethnic background (Leszczensky & Pink, 2015).

Even though homophily is an important factor in tie formation, it can also lead to segregation.

Namely, when the formed ties are only based on similarities (ethnic, religious, etc.), ideas,

knowledge and resources are unequally divided among groups and information is not passed

completely through social networks; this event produces issues such as prejudice and conflict

among individuals (Smith, Van Tubergen, Maas, & McFarland, 2016).

Homophily is a principle that should be considered when studying social networks and friendship

dynamics. People have tendencies to become friends with someone who shares with them a

specific quality, such as gender, age, race, nationality, etc. This principle, drives people to choose

and form their friendships, their networks, and ultimately, their social world. This, so called, social

world has strong significance for the individuals as it shapes or filters the information they receive,

their attitudes and their very own experience of social interaction (McPherson, Smith-Lovin, &

Cook, 2001).

In order to study the element of homophily and friendship formation, most scholars turn into the

most evident institution: schools. Since schools are “relatively closed institutions” in which the

long process of socialization is conducted, it can easily be seen as a ready for analysis institution

by scholars. Furthermore, schools contain a large capacity when it comes to the work of policy

makers since they can treat a considerable number of social problems through schools (Smith, Van

Tubergen, Maas, & McFarland, 2016; Coleman, 1994).

In this research, I intend to study the process of friendship formation at tenth grade (junior year of

high school) among students in a school in Stockholm which mostly includes so called “second

generation immigrants”. The data used is very well suited for the study of the homophily principle

because the start of tenth grade is the start of a new school; therefore, the setting and the social

context is completely new for the student. Further, in this particular school the students come from

85 different schools in different areas of the city; that is, a significant number of them do not know

each other from previous years of education.

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I intend to analyze the existence of homophily principle, with regards to network structure, in

gender, religion, nationality and political opinion among the adolescents in this school. In other

words, the research question is: How is structure in a new social context associated with gender,

national and political homophily among junior high school students?

2 Theory and previous research

The social networks which people establish during adolescent years, have significant effect on

their social and cognitive development. Entrance to high school is, generally, a primary level for

entering a social context outside of family; a place in which students interact, make friends and

form peer groups.

The theoretical discussion in this research is divided into two major parts; theories regarding

gender, political, religious and ethnic/national homophily, and theories regrading social network

structure. In this section, first, I will have a quick browse on friendship dynamics among students;

second, the specified aspects of homophily will be debated; finally, the network structural theories

will be discussed.

2.1 Students and friendship dynamics

A long line of research, during the last decade, has shown the adolescents’ tendency to choose

their friends based on similar characteristics. For instance, Hartup (1993) claimed that adolescents

choose their friends according to similar age, race, sex and social class; he also mentions the

importance of similarity in two general areas of attitude: school related and “contemporary culture”

related. In his opinion homophily in attitude is also a significant factor in adolescent friendship

formation. His work on adolescent friendship formation is of great importance as it showed the

substantial contribution of adolescents’ social network on their development. However, his claims

were quite limited to the notion of similarity as the origin in friendship formation. This view, while

partly true, has been modified when studying the process of adolescent friendship formation in a

social network context.

Roman (2016) conducted a comprehensive research on homophily with regards to individual

background, status of immigration and religious preferences in a school in Stockholm. What is

interesting about this research is that she also takes interest in the outcome of school structure on

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friendship formation. She also considers religious homophily and students’ background, in

addition to ethnic homophily.

Mayer and Puller (2008) also studied the friendship dynamics among students on university

campuses. Their aim was to analyze the tie formation process according to similarities in race,

socioeconomic background, and ability. Their findings suggested that the fraction of friends with

similar ability or parental education is not significantly different from a randomly assigned

network; meaning, students were integrated regardless of the mentioned factors. However, the

same students were racially segmented, indicating a high leniency towards racial homophily.

Mayer and Puller’s research on friendship formation is of substantial significance since they

account for the element of network structure and, most importantly, they emphasize on the subject

of network segregation. This notion is of great importance when it comes to homophily as it can

lead individuals towards prejudice and stereotypical thinking. That is why researchers have worked

on network segregation to be able to come up with a means of measuring and also implementing

policies for reducing it (See: Moody, 2001; Bojanowski & Corten, 2014).

2.2 Types of homophily

Merton and Lazarsfeld (1954) distinguished between two major types of homophily: status

homophily in which friendship is based on similarity in group membership or individuals’ position

in a group and value homophily which is a tendency towards the correspondence of values among

friends. McPherson and Smith-Lovin (1987) introduced a network based mechanism for

homophily. In their theoretical model, they introduced two mechanisms in which homophilous

relations are made: induced homophily and choice homophily. Induced homophily is when a

network is formed around a focus and the individuals in the network are homogenous, any random

network formed around this social focus would be people with similar attitudes or beliefs.

Therefore, this type of homophilous relationship is merely induced by the systematic features of

the network structure. On the other hand, choice homophily in a social network, with

heterogeneous individuals, indicated that people choose others similar to them and this similarity

is not imposed by the characteristic of the network so therefore people choose their social ties

(Ibid). While this theoretical mechanism takes network effects into account, it is rather difficult to

distinguish either mechanism when it comes to empirical analysis. For instance, considering a

social context such as school, both structural constraints and individual choices can be seen when

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it comes to making friends (Kossinets & Watts, 2009); therefore, in this research four types of

homophily which can be empirically analyzed are taken into account. These four types are gender,

religious, ethic/national and political homophily. Afterwards, I will move on to presenting some

arguments regarding the relations of social structure and homophilous relations.

2.2.1 Gender homophily

There is a relatively salient and obvious individual/social identity feature that can breed

homophilous relationships and that is gender. As stated by Shrum et al. (1988) one of the most

consistent findings in studies regarding the peer relations, is the fact that boys and girls are

“relatively isolated”. Even though, they argue that this isolation varies in different ages, the

respective gender specific homophily is present in most age groups.

The fact that children tend to select friends of the same sex is called to attention by numerous

researchers (Morimoto & Yang, 2013; McPherson, Smith-Lovin, & Cook, 2001; Mehra, Kilduff,

& Brass, 1998). Gender homophily is strongly present in childhood; however, as children grow

and reach adolescence, gender homophily starts to decrease (Shrum, Cheek, & Hunter, 1988); this

can be due to the fact that adolescents usually get involved in romantic relationships; therefore,

they, generally, prefer interactions with the opposite sex.

On the other hand, gender homophily can also be seen through structural viewpoints. For instance,

previous research regarding gender homophily in workplace indicated that men tend to have larger

and more gender homophilous networks than women (see: McPherson, Smith-Lovin, & Cook,

2001; Morimoto & Yang, 2013). However, Morimoto and Yang (2013), in their research,

discovered the contrary; namely, women’s tendency for building gender homophilous friendships

was higher than men’s; therefore, when considering gender homophily, one must take into account

the context in which it is being studied. For instance, in the former case, the study was conducted

in a workplace in 1992 and 1997, whereas the latter was done in a graduate school in 2013. As the

working environment was mainly composed by males, it seems rather simplistic to conclude that

men are more likely to form gender homophilous informal networks (see: Morimoto & Yang,

2013).

In conclusion, it can be indicated that even though it varies by age, gender homophily is present in

social networks and it is associated with the structure of any specific social context. Therefore, in

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this research, in addition to analyzing gender homophily with regards to sex, I will try to see the

affiliation of minority/majority on gender homophily (see: section 2.2.5).

2.2.2 Religious homophily

Even though religion is usually considered as an individual matter, it is in fact a social phenomenon

(Cheadle & Schwadel, 2012). Religion is produced and reinforced by social interaction and cannot

be considered, solely, as an individual aspect as it plays a substantial role in organizing social

relations; this fact has been long discussed in sociological texts. For example, Simmel argued that

“the faith which has come to be regarded as the essential, the substance, of religion, is first a

relation between individuals” (Simmel, 1905, p. 366). Furthermore, Durkheim (1965 [1915]) also

discussed the social significance of religion; also, according to Edling, Rydgren and Bohman

(2014) religion is a source of “mutual identification” and social solidarity, in a way that it generates

a group of shared symbols and shared history. Therefore, not only religion helps the individual to

define and give meaning to his/her surroundings (individual level) (Ibid), it also helps shape and

organize the social relations in a specific context.

Needless to say that religion is one of the important factors of making friends in various social

contexts. Numerous researches have shown that religious homophily in fact exists in social

networks. For instance, Cheadle and Schwadel (2012) studied the friendship dynamics of religion

and they concluded that “the youth in this study prefer friendships to those who are religiously

similar” (p.1209). Furthermore, Scheitle & Adamczyk (2009) strongly argue that religion is an

important factor in relation formations. In any case, there are numerous researches with regards to

proving the existence of religious homophily and/or basing the research on religious homophily

(see: Wuthnow, 2007; McPherson, Smith-Lovin, & Cook, 2001; Scheitle & Adamczyk, 2009).

Many scholars have analyzed the reasons for religious homophily; some researchers argue around

the issue of trust; that is, since religion supplies its followers with routine rituals and moral

responsibilities, it gives them a definition for “good people”; therefore, two people of the same

religion have the notion that they both have the same behavioral guidelines which leads to mutual

trust between them (Windzio & Wingens, 2014; Wuthnow, 2007). Further, some claim that

religious homophily is related to rational choice; being a member of any religion requires

individuals to sacrifice time and energy for participating in religious rituals and activities (e.g.

going to church, praying, etc.); hence it would be more beneficial for people to interact with

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someone of their own religion to preserve time and energy (Stark and Finke, 2000). Moreover,

having friends of the same religion is also beneficial in cumulating social capital; numerous

researches have shown that establishing friendship with people of the same religion has a positive

effect on the social capital of the individual (see: Diehl & Ruckdeschel, 2009; Windzio & Wingens,

2014). As a result, having friends of the same religion is beneficial for conserving and/or

cumulating social capital.

The significance of religious homophily has been discussed thoroughly by many scholars.

However, the purpose of the present research does not allow for further discussion around this

subject. It is sufficing to say that religious homophily is a salient feature in social networks.

Therefore, in this research the existence of homophily among the adolescents is analyzed and also

the effect of the network structure on this kind of homophily is studied.

2.2.3 Political homophily

Research regarding the existence and dimensions of political homophily is quite limited (Huber &

Malhotra, 2013), but there seems to be a considerable tendency among adults to associate with

people of the same political opinion (McPherson, Smith-Lovin, & Cook, 2001).

Political homophily can be theoretically distinguished into three types: identity homophily, issue

homophily and engagement homophily; identity homophily is the process of ego’s self-definition

through political notion. For instance, identification with a political party or with an ideological

disposition; according to Huber & Malhorta (2013), political identity is usually formed at early

years in life and continues throughout time. That is why it is believed that political identity is a

group issue and not related to political opinions.

Issue homophily happens when people get sorted in networks through agreement on a political

issue; for instance, economic or foreign policy. Engagement homophily is defined as the tendency

to get in touch with people who are similarly committed to their political or civic rights; for

instance, their engagement in political activities, number of issues that they are willing to vote for

and the amount of interest in joining demonstrations (Huber & Malhotra, 2013).

Political homophily can be considered as a branch of value homophily. As argued by McPherson

et al. (2001) value homophily is a tendency to get in contact with people of the same values and

opinions. However, there are some issues regarding the concept of political, or in general, value

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homophily. Huber and Malhorta (2013) mention induced homophily and convergence as the

sources of difficulty in analyzing political homophily. Induced homophily, indicates the contextual

limitations of making friends in a network. This notion is widely studied by Scott Feld (see: Feld,

1982). The second dilemma can be explaned via the fact that there are other forms of similarity

which are quite stronger in getting people together. For instance, as argued by McPherson et al

(2001) race, sex and religion are the most substantial factors when it comes to homophily.

Therefore, it can be easily argued that similarities in political opinions can be formed among

friends. In other words, according to Huber and Malhorta, “political views and orientations are

malleable over time” (Huber & Malhotra, 2013, p. 8). Therefore, it is rather challenging when

trying to determine political homophily, for in fact it could be a mere convergence.

2.2.4 National/ethnic homophily

Generally, when one begins to discuss homophily, the idea of racial or ethnic homophily comes to

mind; racial similarity creates the strongest grouping and division in society. The main reason for

this argument is salience. That is, when a personal or social characteristic of two individuals are

quite noticeable, it is easier for them to form a homophilic relationship (Mehra, Kilduff, & Brass,

1998; McPherson, Smith-Lovin, & Cook, 2001).

Ethnic homophily, or ethnic segregation is an ever present feature of friendship networks; scholars

claim that it may be the most salient factor when it comes to friendship formation (McPherson,

Smith-Lovin, & Cook, 2001; Smith, Maas, & van Tubergen, 2014; Kao & Joyner, 2004;

Leszczensky & Pink, 2015).

Ethnic or national homophily is considered a highly significant issue, especially among young

adolescents (Smith, Maas, & van Tubergen, 2014); that is, while it is an evident matter in social

networks, ethnic homophily would eventually lead to ethnic segregation and consequently ethnic

or national prejudice which can cause unwanted results (Stark & Flache, 2012). Furthermore, when

it comes to the subject of immigration and so called “second generation immigrants”, a lack of

native friends would result in low language proficiency in the host country, low market skills and

consequently, low chances of finding a suitable career in the future (Ari, 2012; Leszczensky &

Pink, 2015).

Baerveldt et al. (2004) in their work on ethnic boundaries, studied the ethnic boundaries and the

preference for intra-ethnic friendship formation in Dutch schools. In their work, in addition to

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individual inclinations, they acknowledged the effect of social properties on inter-ethnic and intra-

ethnic friendships; they argue that, according to opportunity hypothesis, the ethnic majority, in a

social network, has less preference towards inter-ethnic relations than the ethnic minority. Their

study, however, concluded otherwise, since the Turkish minority preferred intra-ethnic friendship

to a larger extent than the Dutch majority (Baerveldt, Van Duijn, Vermeij, & Van Hemert, 2004).

The point of importance for this research is the consideration of social elements in studying ethnic

homophily. Two hypotheses were presented in this paper which were related to social

circumstances: opportunity hypothesis and social identity hypothesis. According to the latter

hypothesis, people tend to identify themselves with similar groups and differentiate themselves

from “others”. This process can, eventually, lead to prejudice and segmentation (Stets & Burke,

2000).

Sanders (2002) discussed the reasons of boundary formation among immigrants in plural societies;

he discussed the importance of race, parents’ education and their influence on the so called “second

generation” as the basis for establishing homogenous or heterogeneous relationships. Although,

his work seems quite important in studying the effects of social networks in plural societies, it is

in a macro scale and without considering other forms of homogeneity/heterogeneity, such as

gender, attitude or beliefs.

Another example of research on this subject is the work of Shrum and Hunter (1988). In their

research, they analyzed gender and racial homophily among students in school. Using a

longitudinal data, they determined that gender segregation started declining from junior high

school, but racial homophily started to increase through time. Even though their research is a

middle-range study, Shrum and Hunter fail to control for various confounders such as family

background and religion; furthermore, their categories of different races seemed quite limited.

However, they presented interesting results which was the foundation for later studies on gender

and racial homophily in schools and universities.

Even though ethnic homophily has its negative effects, most adolescent social networks are based

on this phenomenon. There have been various policies implemented for reducing ethnic homophily

and segregation (see: Stark & Flache, 2012), but this element has been one of the most powerful

in the process of friendship formation (McPherson, Smith-Lovin, & Cook, 2001).

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There are two arguments regarding ethnic homophily that will be discussed here. First, Smith &

van Tubergen (2014) who base their argument upon cultural similarities. They are of the opinion

that “adolescents are likely to prefer friends who have similar leisure activities as it helps them in

the development of their identity and self-esteem” (p. 35); cultural similarity makes it easier to

find a mutual leisure activity among friends, which can be enjoyed by all of them. Therefore, with

respect to cultural similarity, adolescents prefer making friends with someone of the same ethnic

background. The second argument is, once again, extracted from rational choice theory. While

starting a friendship tie and maintaining it is a rather costly activity, having to form the tie with

someone of the same ethnic background usually decreases these costs and is more rewarding.

(Lazarsfeld & Merton, 1954). When ego tries establishing a tie with someone of another ethnic

background, he/she would spend the same time and energy and probably not get the same reward

as in an ethnic homophilous relationship (Leszczensky & Pink, 2015; Windzio & Bicer, 2013).

In the present research, national/ethnic homophily is analyzed using the respondents’ and their

parents’ birthplace. Also, the relations between network structure and national/ethnic homophily

will be studied.

2.3 Homophily in social network In the previous sections, various features of homophily were discussed. In this section, the aim is

to present arguments regarding the effects of network structures on homophilous relations.

The theoretical arguments mentioned above mainly concentrate on the existence of homophily in

social networks. However, they usually have overlooked the affiliation of the structure of a social

network on homophily. Namely, considering a social context such as school, both structural

constraints and individual choices can be seen when it comes to making friends and it is rather

complicated when these concepts are studied in real life social networks (Kossinets & Watts,

2009).

With regards to the critics to the aforementioned theories, in this research the theory of

distinctiveness will be discussed. Distinctiveness theory suggests that “People in a social context

tend to identify with others with whom they share characteristics that are relatively rare in that

context” (Mehra, Kilduff, & Brass, 1998, p. 442). For instance, two black people are more likely

to get in contact in a crowd of white people than in a crowd of black people. According to this

theory, the notion of rarity of a characteristic in a social network, makes that characteristic a lot

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more salient for the ego and therefore elevates the chances of forming a tie with an alter of the

same characteristic.

Distinctiveness theory is quite useful when it comes to situations where individuals have just

entered a social context and seek new friends; for instance, the first year of high school. It is during

high school that adolescents develop the idea that they are social beings, thus they try to identify

themselves with others (Cheadle & Schwadel, 2012). With respect to this notion, one or more of

personal characteristics of the adolescents will be rare and consequently more salient. The

argument here is that adolescents will identify themselves with that specific feature of their identity

and hence form friendship based on rare similarities.

In conclusion, I hypothesize that gender, religious, political and national/ethnic homophily is

promoted when these phenomena are rare in a social context (i.e. in the studied school).

In the present research, however, I intend to study friendship ties in relation to gender, religion,

national and political homophily. In addition, it is in this study discussed if homophily, with respect

to the mentioned aspects, also is influenced by the number of individuals sharing the specific

characteristics. In other words, accompanying the theories supporting gender, political and

national homophily, I will also test the plausibility of distinctiveness theory and Blau’s theorem

on social structure. Blau discusses the quantitative characteristics of social structure in analyzing

inter-group association among majority and minority groups in a social network. In his opinion,

Firstly, the intergroup involvement of the minority exceeds the majority; secondly, the probability

of intergroup relations decreases with increasing group size and thirdly, the more a majority

discriminates against a minority, the smaller the difference between the majority and the minority

intergroup relations (Blau, 1977).

Furthermore, this research argues that the study of social networks among adolescents is quite

important. Cheadle et al (2012), for instance are of the opinion that while adolescence is the period

where individuals are highly resistant to the fact that they are social beings, but at the same time,

they are entering a social space which is separate from home. Therefore, in this research, it is

argued that the mechanism adolescents use to find and make friends, will continue throughout their

social life.

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Overall, the importance of this research lies in two facts; first, the argument that social structure

of the school is associated with the homophilic relations at school; second, the importance of the

friendship dynamics in teenage years.

3 Research question

In this study, the aim is to the study the probability of existence of friendship ties with accordance

to the homophily principle. The types of homophily analyzed are gender, religion,

nationality/ethnicity and political opinions. In addition to this subject, this research intends to see

the association between homophilous friendship ties and the prevalence of the variables that the

homophily is based on. Therefore, the results will be analyzed with the distinctiveness theory in

mind, to see if individuals with minority characteristics are more prone to form ties with each

other.

4 Data

The data which is going to be used in this research is assembled by Sara Roman and is gathered

from the cohort that started grade 10 in upper secondary education in a school in Stockholm at

three time points (October 2012, May 2012 and January 2013) during the academic year

2012/2013. It includes a total of 115 individuals and contains information about the social network

in the cohort as well as individual characteristics of the students. The data was collected by Roman

by means of questionnaires that were distributed to the students in their classrooms during class

time. Each classroom was visited at least twice. To reduce the ethical issues of the survey, the

students were thoroughly informed about the detail of the research, beforehand; further, the

identity of the school and the respondents were protected; also, participation in the research was

voluntary and students could withdraw from filling out the questionnaire anytime they wanted.

The data collection was approved by the regional committee for ethical vetting (see: Roman,

2016).

The school was not chosen randomly; Roman had chosen this specific school since it contained a

lot of students who were born in another country or were, so called, “second generation”

immigrants. Therefore, the data and the analyses, here, are not necessarily representative of all of

the adolescents in Stockholm.

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Individual characteristics include information about demographic characteristics (such as, age,

gender, etc.), ethnic and religious background, political orientations, status of mental and physical

health and spare time activities.

Network data are gathered by asking the students to name three of their closest friends in school

and discovering the quality of their friendships by asking whether they spend time with their

friends outside of school and if they can talk to these friends about their personal problems. The

cases are then coded into numbers and they are so called “edge lists”, basically a list of pairs that

have a relation. Every row represents a pair that was reported as a response to the question "with

which other students in the cohort have you spent time after school during the last three weeks?"

(Roman, 2016).

Political preference measures are questions regarding the respondent’s tendency towards left or

right wing parties and also the political parties they would vote for if there was an election.

Religious affiliation was measured with questions regarding the importance of religion for the

respondent and his/her parents, and also the respondent’s own religion. National affiliation, as

contentious as it is, was measured by the respondent’s parents’ birth country.

In consideration of the fact that this study focuses on the formation of immediate ties, longitudinal

data is not necessary for analyzing the research question. Therefore, only the first wave of the

dataset is going to be used for analysis. Furthermore, some of the questions that were necessary

for the analysis, were not asked from the respondents in the second and/or third wave of data

gathering; hence, those waves were not considered in the analysis.

4.1 Dependent & Independent variables

The dependent variable is whether two students know each other or not. Hence, the subject under

study is the possible link which can exist between each pair of individuals in the data (the

extraction of the dependent variable is further discussed in section 5). The independent variables

are being the same gender, same religious affiliation, having the same religion, mutual significance

of religion for the respondents’ parents, same birth country for at least one of the parents.

For analyzing homophilous relations based on gender, a binary variable was developed to show

whether two persons in the two by two network data are of the same gender or not. Second, two

variables were created: 1. At least one in the pair is male 2. At least one in the pair is female to see

14

the difference in friendship formation between boys and girls; and third, two binary variables were

made for both male and female friendships.

Regarding religious homophily, in the questionnaire participants were asked to indicate their

religion. The answers included no religious affiliation, Christian, Jewish, Muslim, and other. The

“other” option was used as the reference variable in the analysis. In the network data a binary

variable was created to see whether two students were of the same religion or not.

The second variable is the importance of religion for the participant. Participants were asked about

the significance of religion for them. The answers ranged from “very important” (4), “fairly

important” (3), “not very important” (2) and “not at all important” (1). These answers are recoded

to important (choices 3 and 4) and not important (choices 1 and 2). The same importance for

religion is created to see whether mutual significance of religion is important in friendship

formation.

With respect to parents’ religiousness, a merged variable was made that indicated the significance

of religion for at least one parent from both sides of the network data. It is worth mentioning that

since the frequency of the data is not quite high, this merged variable was made to make the models

more sensible.

With regards to the effect of network structure, the “same religion” variable was divided into three

categories: nonreligious friendships, Christian friendships and Muslim friendships. These

categories indicate the possibility of friendship if both students are of same religion. However, the

variable for Jewish friendship was omitted since there were no such cases in the data that both

students were Jewish and friends.

For measuring national/ethnic homophily, the countries in which the students or the parents of the

students were born, were categorized into five regions; these regions include Europe, Middle East

and North Africa, Sub-Saharan Africa, Sweden and other regions. Other regions include students

(or their parents) born in Bangladesh, Bolivia, Colombia, India, Pakistan, Peru, Sri Lanka,

Thailand, Turkey, and Uzbekistan; the reason for grouping these countries as “other” was mainly

due to the fact that the frequency for students from these countries were low. These categorizations

were based on Sara Roman’s categorization of the birthplace variable, with the exception of

“European” categorization (see: Roman, 2016). Afterwards, three sets of binary variables for

15

mutual birthplace were created; one for if two students shared a birthplace, another to see if at least

one parent of two students shared a birthplace and a third, to see if both parents of two students

had the same birthplace.

Moreover, for seeing the effect of the structure of the existing social network on different types of

national/ethnic homophily there were nine variables created. The first four was to analyze the

probability of friendship among those born in the same region; the other are five variables, also

bianry, to see the effect of students from different regions on the possiblity of them making friends.

Therefore, five variables were created for four regions and one “other” regions. These variables

are to see if being born in a region affects the probablity of making friends. The results for national

or ethnic homophily and the probability of being friends are shown in table seven.

For identity homophily, the operationalized predictors were being interested in politics, voting for

a political party if there were a hypothetical election and political orientation (right and left wing).

The focus in this research is whether or not students are similar in these indicators which would

imply analogous political identity. Nonetheless, from all these variables only voting for a similar

political party was used in the model, due to lack of sufficient cases and a lot of missing values.

Engagement homophily is divided into three political activities: engaging in political meetings,

participating in demonstrations and being a member of a political organization. These variables

were, at first, merged into a single index of political engagement. However, since there were a

high number of missing values in the data, the engagement index was dropped and only

participating in political meetings were used in the regression models (see table eight)1.

Control variable is a binary variable indicating if two students attended the same school in ninth

grade. This variable was controlled to see if possible previous friendship is also a factor in

friendship network formation. Furthermore, same gender friendship was also used as a control

variable in all regressions (except the one where gender was the main interest, obviously). Also,

1 Within the subject of issue homophily, I concentrated on the views of students regarding the issue of migration.

With respect to this issue, an index was created regarding their opinion about government’s policy when it comes

migrating to Sweden and accepting refugees. These policies included the money spent on immigrants, the quantity

of immigrants and refugees moving to Sweden, whether immigration is a beneficial phenomenon in Sweden and the

responsibility of rich countries for accepting refugees. This index was also dropped due to lack of data.

16

considering the effect of propinquity on tie formation, I have also controlled for being in the same

classroom.

5 Method of research

There were two sets of data at my disposal. One containing network data, which is a list of pairs

who have established friendships, and one containing all respondents’ answers to the

questionnaire. For the purposes of the study, the two datasets were merged in the form that every

possible relationship between each student was put together, then a binary variable was defined to

show which pair had a relationship in real life. Afterwards, all the other variables were merged

into this dataset for both the first column respondents and the second column respondents to be

able to compare their answers and find out the similarities and the differences. Conclusively, I had

two datasets, one containing information regarding the real descriptive characteristics of the

research group, and one consisting of network information and the comparison of their answers.

In order for the reader to better understand the method of research, two tables are presented below.

The table on the left is a group of hypothetical students in a school and the table on the right is a

matrix of all possible ties which can be formed. The value zero means that there are no ties between

the two individuals and value one means that a dyad (tie) exists. The black cells in diagonal of the

matrix indicates that an individual, per definition, cannot befriend him/herself (i.e. there are no

entries in the diagonal). Further, since the matrix is symmetric (e.g. if there is a relation between a

and e, there must be a relation between e and a, etc.) the part of the matrix which is above and to

the right of the diagonal holds no information, since this information should be redundant. As seen,

there are 45 possible ties in this network of 10 individuals and 13 of them are realized as friendship

ties. This is how the dependent variable was generated in the research.

17

Table 1. How the network data (dyads) were produced

Respondents a b c d e f g h i j

a a

b b 0

c c 0 0

d

d 0 0 0

e

e 1 0 1 0

f f 0 1 0 0 0

g g 0 0 0 0 0 1

h h 0 1 0 0 0 1 1

i i 1 1 0 0 1 0 0 0

j j 1 0 0 1 0 0 0 1 0

Hence, the entity under study is if a friendship link exists between each pair of individuals. Table

two shows a small excerpt of how the analyzed data generated from the matrix looks like. The

subject under study (the dependent variable in the subsequent analysis) is the variable called

friends, in the table below. Now, variables such as if the two students are of the same gender or

not can be added.

Table 2. An excerpt of how the data looks like

Individual 1 Individual 1 Friends Same sex

a b 0 1

a c 0 0

a d 0 0

a e 1 1

a f 0 0

a g 0 1

a h 0 0

a i 1 1

a j 1 0

b c 0 0

b d 0 0

b e 0 1

As pointed out, the units of analysis in the research are the possible dyads, the ties which are or

are not realized between two students in the school. The analysis is seeing how the odds that a tie

actually exists is associated with e.g. whether the pair of individuals are of the same sex or not.

18

Since the dependent variable is binary, logistic regression model was used to test the hypotheses.

Analysis were conducted using statistical software Stata (Version 13.0, StataCorp, College Station,

Texas).

The chosen school for the study has special characteristics. It is not a representative of other

schools in the Stockholm region. Further, the data is from all the students who were present in the

school; that is, the analysis is conducted with the research population and not a research sample.

Therefore, significance of the odds ratio is not relevant in this research. That is why instead of

significance, robustness of the coefficients is considered in the analysis. A robust coefficient, in

this research, is defined as a coefficient with a relatively low standard error. Therefore, in the

analysis, the focus is on the relative value of the standard error to the odds ratio to see the

robustness of the coefficient.

6 Results

A total number of 111 students were analyzed in this research. As seen, this number is lower than

the original amount, which was 115. This is because in the first wave, there were four students

missing (they were absent on the day or were not yet registered at school). Table three gives an

overview of different characteristics of the students in this school.

Table four shows the distribution of the dependent and independent variables. These variables are

mostly binaries to measure if two students are of the same characteristics. It is worth mentioning

that the high number of n in this table is due to the fact that the frequency for the independent

variables were extracted from the crossed dataset. That is the dataset in which the data for the first

wave were merged and crossed with the network data.

19

Table 3. Frequency distribution of gender, religion, birth place (mother, father and the student) and political preference and

engagement.

Frequency Percent Cum. Perc

Gender Male 43 38.74 38.74

Female 63 56.76 95.5

Missing 5 4.5 100

Religion Non-religious 17 15.32 15.32 Christianity 39 35.14 50.45

Judaism 1 0.90 51.35

Islam 41 36.94 88.29 Other 8 7.21 95.50

Missing 5 4.50 100.00

Father's birthplace Europe 9 8.11 8.11

Middle East and North Africa 22 19.82 27.93

Sub-Saharan Africa 33 29.73 57.66

Sweden 25 22.52 80.18 Other 13 11.71 91.89

Missing 9 8.11 100.00

Mother's birthplace Europe 10 9.01 9.01

Middle East and North Africa 20 18.02 27.03

Sub-Saharan Africa 33 29.73 56.76

Sweden 29 26.13 82.88 Other 11 9.91 92.79

Missing 8 7.21 100.00

Student's birthplace Europe 3 2.70 2.70

Middle East and North Africa 11 9.91 12.61

Sub-Saharan Africa 13 11.71 24.32

Sweden 68 61.26 85.59 Other 8 7.21 92.79

Missing 8 7.21 100.00

Political party2 Moderaterna 16 14.41 14.41

Vänsterpartiet 5 4.50 18.92

Socialdemokraterna 32 28.83 47.75

Miljöpartiet 3 2.70 50.45 Blank vote 2 1.80 52.25

Would not vote 5 4.50 56.76

Missing 48 43.24 100.00

Engagement in political meeting Yes 21 18.92 18.92

No 71 63.96 82.88

Missing 19 17.12 100.00

n 111 100.00

2 Name of the political parties are in Swedish. No other political party was mentioned.

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Table 4. frequency distribution of similarity between all possible pairs of students and observed friendship formation.

Frequency Percent

Gender homophily

Same gender

Yes 2856 45.39

No 2709 43.05

Missing 540 8.85

Total 6105 100

Religious homophily

Same religion

Yes 1725 27.42

No 3840 61.03

Missing 540 8.85

Total 6105 100

Same

importance

(religion)

Yes 2773 44.07

No 2583 41.05

Missing 749 12.27

Total 6105 100

National/ethnic homophily

Same birthplace

(student)

Yes 2299 36.54

No 2954 46.95

Missing 852 13.96

Total 6105 100

Same birthplace

(at least one

parent from

each side)

Yes 629 10

No 4624 73.49

Missing 852 13.96

Total 6105 100

Political homophily

Vote for the

same party

Yes 640 10.17

No 1313 20.87

Missing 4152 68.01

Total 6105 100

Engage in

political

meetings

Yes 210 3.34

No 3976 63.19

Missing 1919 31.43

Total 6105 100

Observed friendship formation

Friends with

each other

Yes 300 4.91

No 5805 95.09

Total 6105 100

6.1 Gender homophily

As seen in table five, the same sex friendship has an odd above one; that is, holding everything

else constant, the odds of two students knowing each other is higher when they are of the same

gender, compared to two students of different gender. Compared to the odds ratio, the relatively

low standard error of this odds ratio indicates that the coefficient is robust.

However, while the odds ratio of Model 1 is 2.51, the odds ratio of Model 2 is 1.31. This could be

because in the first model the probability of males making friends is calculated, whereas in the

second model the probability for females making friends is estimated. The above one ratio of “one

21

in the pair is male” and the below one ratio of “one in the pair is female” is an indicator that a

group of friends is more likely to form if it includes boy students than girl students. This is in line

with Shrum’s theory that boys tend to form large networks and girls have leniency towards forming

smaller networks (Shrum, Cheek, & Hunter, 1988). Moreover, distinctiveness theory is supported

when comparing male and female friendship coefficients in models 3 and 4 (see: Mehra, Kilduff,

& Brass, 1998). As seen in model 3 and 4 in table five, individuals are more prone to form same-

sex friendship ties than mixed-sex friendship ties. This goes for both men and women. However,

the odds for same-sex friendship (compared to mixed-sex friendship) is lower for women than

men. Further, a Chi-squared test indicate that this difference is highly robust. This number also

indicates the effect of distinctiveness theory on friendship formation when it comes to sex.

The rather intriguing part of this table are odds ratios for being in the same class and being in the

same school at ninth grade. As seen, the odd ratio for same ninth grade, has higher standard error

when the “same class” control variable is entered in the model. The standard error of the “same

class” is relatively small compared to the predicted odds ratio, which shows the robustness of the

variable.

Table 5. Maximum likelihood logistic regression of gender homophily. Dependent variable is the odds of two students being

friends. Control variables are a binary if they were in the same school and a binary if they were in the same classroom. Results

are presented in odds ratio. Standard errors in parentheses.

Model 1 Model 2 Model 3 Model 4

Independent variables Same sex friendship 2.516 1.310

(0.348) (0.165) One in the pair is male (at least) 1.921

(0.272) One in the pair is female (at least) 0.520

(0.074) Female friendship 1.268 1.310

(0.153) (0.165)

Male friendship 2.377 2.516

(0.31) (0.348)

Control variables Same ninth grade 2.297 2.297 3.737 2.297

(1.161) (1.161) (1.754) (1.161)

Same class 8.278 8.278 8.278

(0.935) (0.935) (0.935)

Log Maximum likelihood -1240.69 -1240.69 -1432.09 -1240.69

n 5562 5562 5562 5562

22

6.2 Religious homophily

In this type of homophily, like national or ethnic homophily, having the same religion is not the

only important factor in analysis; since the data deals with junior high school students, the element

of religion among the parents of the students is also considered in the regression models.

Table 6. Maximum likelihood logistic regression of religious homophily. Dependent variable is the odds of two students being

friends. Control variables are a binary if they were in the same school and a binary if they were in the same classroom. Results

are presented in odds ratio. Standard errors in parentheses.

Model 1 Model 2 Model 3 Model 4 Model 5

Independent variables

Same religion 1.445 1.432 3.518 3.588 2.435

(0.163) (0.164) (1.973) (2.012) (1.455)

Same importance (student) 1.284 1.254 1.285 1.302 1.334

(0.144) (0.152) (0.146) (0.148) (0.158)

At least one parent from both sides (merged) 1.075

(0.153)

Same religion friendship*

Nonreligious 0.358 0.356 0.479

(0.228) (0.226) (0.323)

Christian 0.371 0.362 0.552

(0.213) (0.207) (0.337)

Muslim 0.443 0.431 0.666

(0.253) (0.246) (0.405)

Control variables

Same ninth grade 6.000 3.917

(2.446) (1.724)

Same class 7.718

(0.904)

Log Maximum likelihood -1328.525 -1328.397 -1326.89 -1319.563 -1154.603

n 5148 5148 5148 5148 5148 *Reference variable is "other religions"

As seen in table six, having the same religion is an important factor in making friends. In almost

all the models represented in the above table same religion variable is has an odd above one and

relatively low standard errors. However, this is not the case with the odds ratios indicating how

the association between realizing a friendship link and religious similarity vary between different

religions. In the last model, as the control variable, “same class”, is entered in the model, the odds

ratio for having the same religion decreases and the relatively high standard error suggests a fragile

coefficient. Therefore, while being in the same religion at first seems to be an important factor in

forming friendship ties, being in the same classroom, as a social focus (see: Feld S. , 1981) is more

23

substantial (at least for all other religions than Islam, see further interpretations of the results

below)3.

In the second model, I have controlled for the importance of religion among parents; more

precisely, the similarity of significance (or non-significance) of religion in between at least one

parent from both sides. The odds ratio for this variable indicates that importance of religion in the

family is not an important factor in tie formation among the students. However, the odds ratio for

importance of religion for the students themselves in the other models shows that the importance

of religion for the individual is a factor for friendship formation

The network structure effect, as mentioned, has been studied through dividing same religion

friendships into three categories. The net effect for each religion (each category) is the odds ratio

of same religion variable plus the odds ratio for that religion. For obtaining the net effect and

consequently seeing which religion increases the odds of being friends the linear combinations of

estimates was calculated.

The results for three linear combinations suggest that since only the odds ratio for Muslim students

was high and robust (comparatively lower standard error). The ratio was 1.53; that is, the odds that

a tie exists between two random Muslim students is 1.53 times higher than the odds that a tie exist

between two random students of different religions. Christianity and non-religiousness does not

give a higher probability of intergroup friendship formation compared to friendship between

different religious groups.

6.3 National/ethnic homophily

There are several factors to be considered in this type of homophily. First, the existence of national

or ethnic homophily among students in the school. Second, the effect of parents’ birthplace on this

form of homophily and Third, the effect of the actual social structure on the existing homophily.

3 For seeing the association of social focus and probability of friendship, an interaction between same classroom and

same religion is needed; however, due to data limitation, this analysis could not be performed.

24

Table 7. Maximum likelihood logistic regression of national/ethnic homophily. Dependent variable is the odds of two students

being friends. Control variables are a binary if they were in the same school and a binary if they were in the same class. Results

are presented in odds ratio. Standard errors in parentheses.

Model 1 Model 2 Model 3 Model 4 Model 5 Model 6

Independent variables

Same birthplace 1.613 1.504 1.511 3.362 3.024 1.712

(0.178) (0.171) (0.17) (1.686) (1.663) (0.348)

At least two parents of both students share birthplace 1.516 1.508 1.441 1.441

(0.224) (0.223) (0.225) (0.226)

Both parents of two students 1.710 (0.292)

Same region friendship*

Middle East and North Africa 0.436 0.447 (0.314) (0.344)

Sub-Saharan Africa 0.256 0.324

(0.182) (0.246) Sweden 0.449 0.491

(0.224) (0.269) Variables relevant to region

At least one in the pair is European 1.084

(0.357)

At least one in the pair is ME or NA 1.354

(0.324)

At least one in the pair is African 1.222

(0.282)

At least one in the pair is Swedish 1.754

(0.455)

At least one in the pair is from other countries 1.187

(0.194)

Control variables

Same ninth grade 2.47 2.475

(1.361) (1.371)

Same class 7.631 7.746

(0.903) (0.918)

Log Maximum likelihood -1290.5364 -1286.8022 -1286.049 -1284.9872 -1122.8703 -1120.9246

n 4947 4947 4947 4947 4947 4947

*Reference variable is other regions

In the first model, only the variable for same birthplace was controlled to see if the association is

above one. In the second and third model, I controlled for the birthplace of parents and its relations

with the odds of two students being friends. The robust and above one odds ratio of the two

variables in both models presents the association between the similarity of the students’ parents

birthplace and the odds of them being friends.

As seen, in the fourth and fifth model, the variables for the same region friendships are added;

these three variables (friendships between Middle East and North African, Sub-Saharan African

and Swedish students) are part of the same birthplace variable; therefore, a linear combinations of

estimators has been conducted to see the effect of same region friendships on the probability of

students being friends with each other.

25

The result from the linear combination of the aforementioned variables indicates that the joint

effect of same birthplace and being born in Sweden is 1.60; that is, the odds that a friendship tie is

realized is 1.60 times higher if both students are born in Sweden compared to the case where they

are not born in the same region. This number also has a relatively lower standard error compared

with the odds ratio which is an indicator of robustness. Therefore, the odds ratio of being friends

is heightened for two individuals if they are both born in Sweden. However, the odds ratio for the

variable same birthplace is not robust for students who were born in Africa (Northern and Sub-

Saharan) or the Middle East.

As seen, in the last model, I have also controlled for the odds of making friends with students from

the aforementioned regions. As seen, the odds ratios are above one but they have relatively large

standard errors. Hence, it is risky to draw any conclusions that being from certain regions associate

with the process of friendship formation.

6.4 Political homophily

The three dimensions of political homophily, according to Huber, are identity homophily,

engagement homophily and issue homophily (see: Huber & Malhorta, 2013). In the analysis, due

to lack of data, only two of these dimensions, identity homophily and engagement homophily were

examined.

Table 8. Maximum likelihood logistic regression of political homophily. Dependent variable is the odds of two students being

friends. Control variables are a binary if they were in the same school and a binary if they were in the same class. Results are

presented in odds ratio. Standard errors in parentheses.

Model 1 Model 2

Independent variable

Vote for the same party 1.676 1.698

(0.352) (0.383)

Participating in political meetings 2.491 3.148

(0.791) (1.14)

Control variable Same ninth grade 3.693

(3.289)

Same class 14.644

(3.813)

Log Maximum likelihood -371.779 -300.299

n 1711 1711

Table eight consists of only a variable or political identity homophily (voting for the same party)

and engagement homophily (participating in political meetings).

26

In the first model, I analyzed the odd ratio of voting for the same party and participating in political

meetings among students. The odds ratios indicate that the odds of a realized tie is 1.68 times

higher if the two students voted for the same political party and the ratio is even higher if they

participate in political meetings (2.49).

In the second model, with the control variables, the values of the odds ratio for political homophily

is above one and have lower standard error. Therefore, it can be concluded that political homophily

is associated with the odds of two students forming friendship ties.

6.5 Homophily and friendship

In the final section of the results all of the factors described above are put into one logistic

regression model; in this model the aim is to see the association of the four types of homophily,

put together, with the probability of friendship formation; however, as seen in table nine, the “same

gender” and “same religion” variables were omitted from the models to see the association of the

sub-types of the different kinds of homophily with friendship formation and also to test the

significance of their odds ratios when analyzed in one model.

27

Table 9. Maximum likelihood logistic regression of gender, religious, national and political homophily. Dependent variable is the

odds of two students being friends. Control variables are a binary if they were in the same school and a binary if they were in the

same class. Results are presented in odds ratio. Standard errors in parentheses.

Model 1 Model 2

Independent variables Gender homophily

Male friendship 2.590 3.296

(0.384) (1.094)

Female friendship 1.340 2.421

(0.189) (0.719)

Religious homophily At least two parents of same religion 1.297 1.066

(0.193) (0.303)

Not religious 0.713 (0.264)

Christian friend 1.195

(0.22) Muslim friends 1.997

(0.309) National/ethnic homophily

At least two parents of same region 1.556 2.814

(0.255) (0.807)

ME or NA friends* 0.836

(0.477) Sub-Saharan African friends 1.031

(0.557) Swedish friends 1.597

(0.204) Other regions friends 3.584

(1.978) Political homophily

Vote for the same party 1.37

(0.373)

Participating in political meeting 4.518

(1.868)

Control variables Same ninth grade 3.125 5.451

(1.751) (5.494)

Same class 7.273 17.372

(0.891) (5.291)

Log Maximum likelihood -1038.3411 -236.9847

n 4750 1540

*ME: Middle East, NA: North Africa

As seen, there are two models represented in table nine. This is due to the fact that the variables

for religious and national homophily could not be put together with the variables for political

homophily. The reason for this could be, primarily, because of a relatively small number of cases

(especially in political homophily). In fact, it seems like many respondents had answered either

questions on political views or on religious and national issues. Hence, putting all factors in the

same regression would reduce n too much, and the models would be shaky.

According to table nine, gender homophily raises the odds of being friends among students in

school. However, being in the same religion is not a robust factor in making friends, except for

students of the Muslim faith. The odds of two students being friends is heightened if the parents

of the two students were born in the same region. In this category, the odds for Swedish born

28

students are high with a relatively low standard error. This can be because most students stated

that they were born in Sweden; so, this also can be due to a relatively larger n for Swedish born

students than students born in other region and/or countries.

In conclusion, while religious homophily does not seem to be an important element in tie formation

(except for Muslim students), the other categories of homophily have robust associations with the

odds of making friends in school.

7 Discussion

The purpose of the present study is to analyze the probability of friendship formation with regards

to the homophily principle and network structure among junior high school students (10th grade)

in a school in Stockholm.

The types of homophily studied in this research were gender, religious, national/ethnic and

political. In addition to these four types, I also aimed to see the affiliation of school network

structure with the process of firendship formation. The research is divided by these four types of

homophily, as to theoretically and emprically analyze them among adolescents in a high school.

Logistic regression methods were used to see the association of different types of homophily and

the odds of two students being friends.

The term “homophily” was first coined by Lazarsfeld and Merton in 1954 when analyzing

friendship as a social process. Homophily principle has high significance when it comes to

friendship formations as social networks are not randomly distributed (McPherson, Smith-Lovin,

& Cook, 2001). People have tendencies to become friends with others of the same characteristics.

For instance, they prefer to form a tie with people of the same religion (Windzio & Wingens,

2014), the same nationality or ethnicity (Leszczensky & Pink, 2015) or the same gender (Shrum,

Cheek, & Hunter, 1988). Individuals also favor people who have the same opinions regarding

political issues, moral values, etc. (Lazarsfeld & Merton, 1954; Huber & Malhotra, 2013; Birds of

a feather: Homophily in Social Networks, 2001).

Homophily principle must always be considered in social network analysis. As mentioned above,

people are always keen on establishing connections with others whom they share a specific quality;

such as, gender, race, religion, etc. This tendency guides individuals in the process of friendship

formation and establishing their social network, hence shaping or filtering the information they

29

receive, their attitudes, values and their experience of social interaction (McPherson, Smith-Lovin,

& Cook, 2001).

In this research, the probability of friendship formation was studied in a school in Stockholm.

Schools are quite popular among scholars when it comes to social network analysis. This can be

due to the fact that they are “relatively closed institutions” (Smith, Van Tubergen, Maas, &

McFarland, 2016, p. 1224) in which the long process of socialization is conducted. Furthermore,

it is also an easy target for policy makers as they can treat numerous social issues through schools

(Smith, Van Tubergen, Maas, & McFarland, 2016; Coleman, 1994).

In the present study, in addition to homophily, I have also tried to analyze the network

characteristics with respect to distinctiveness theory (see: Mehra, Kilduff, & Brass, 1998).

A number of notions can be concluded from the results of this research. First, gender homophily

is existent among adolescents in high school. In addition, according to the results, the odds of boys

being friends with each other is higher than the odds of girls forming ties with each other. However,

it seems rather simplistic to indicate that males are more prone to forming gender homophilous

relations than females (Morimoto & Yang, 2013). Seeing as the majority of the students are female

(see table five), this can be explained by distinctiveness approach (Cheadle & Schwadel, 2012).

That is, since the majority of the students are female, the male monirity would have a stronger

tendency towards forming gender homophilous ties.

Second, In contrast to many researches in the field of religious homophily (McPherson, Smith-

Lovin, & Cook, 2001; Scheitle & Adamczyk, 2009; Windzio & Wingens, 2014), while religious

homophily was proven, when analyzed separately, in the final model with all the factors considerd,

religious homophily did not seem to be an important factor in tie formation among non-religious

or Christian. However, Muslim students show a significant tendency towrds being friends with

Muslim students. Since these students were not a minority in this particular school, distinctiveness

approach cannot explain this issue.

National/ethnic homophily is present among adolescents of the school. A positive association was

found between the birthplace of the parents of the students and the odds of them being friends.

However, this positive association is not seen when it comes to analyzing the birthplace of students

according to the various regions (Middle East and North Africe, Sub-Saharan Africa, Sweden, and

30

other). The results indicate that when two students are born in Sweden, they have higher odds of

being friends. However, this increased probability does not hold for students who are born in the

other mentioned regions. These results can be debated since the majority of the students had

indicated that they were born in Sweden; in other words, while the parents could have been born

in a country outside Sweden the child could have been born in Sweden, the so-called “second

generation” immigrant. Furthermore, the students born in what was labeled as “other regions”

(which include very few students) have heightended probability of being friends. That is to say

that since these students were the minority in the school, the tendency to become friends with each

other was higher than students from the mentioned regions.

For testing the political homophily among students Huber & Malhorta (2013) theoretical

discussion was used. They divided the political homophily into indentity homophily (voting for

the same party in this research), engagement homophily (attending political meetings) and issue

homophily. While, when analyzing separately, the variables related to identity and engagement

homophily were positively associated with the odds of friendship tie being realized, only

participating in political meetings (engagement homophily) was robust. However, because of a

high number of missing data regarding political orientation in the survey, I could not analyze the

third dimension (issue homophily) of political opinion similarity and its association with friendship

formation.

As it is shown in this research, similarity plays an important role in friendship formation. The

results of this research indicated the importance of homophily in social networks. As opposed to

previous research, for instance Shrum et al. (1988), which claimed that gender homophily

decreases significantly during adolescence, this research showed that this type of homophily still

exists, even as a teenager. Further, while a number of researches claim of the existence of religious

homogeneity in friendship formation among adolescents, the present work showed that religion

does not play an important part in friendship formation, except for Muslim students. Moreover,

national/ethnic homophily, parents’ birthplace to be more precise, still is an important factor in tie

formation among teenagers, as it has been proven by other researches, as well. A rather intersting,

even if not very unexpected, finding of this research was the high and positive odds ratio for the

control variable “same class”. If a classroom is considered a social focus (see: Feld S. , 1981), this

ratio proves the highly important role of social foci in tie formation among adolescents. However,

31

due to lack of data further examination of this issue (e.g. the interplay between the examined

homophily issues and social foci) could not be conducted.

Even though this thesis has shed some lights on how the social networks are formed, there were a

number of limitations in the process of analysis. First and foremost, the main challenge faced in

the analysis, was the low number of respondents. As seen in table three, only 111 respondents were

analyzed in the research. Although the network data was sufficient for analysis, there were a few

problems when I wanted to enter interactions into the models. This issue became more evident in

the analysis related to political homophily which has led to two final models (see results). On

account of these limitations, further investigation regarding the effect of social network structure

according to distinctiveness approach could not be pursued. Therefore, while I was able to show

the existence of homophilous firendships among adolscents, the investigation regarding the effect

of network structure on homophilous relations remains unreliable. Further, the unit of analysis in

the present research is the ties (dyads) formed between two students. The individuals themselves

were not considered in the analysis. This factor can create issues regarding the individual

characteristics e.g. if a student has more links than the total average. Although the students were

asked to name only three of their friends in the school, there is still a possibility of bias in the

research.

Furture research regarding the mechanisms involved in adolescents’ friendship formation should

involve a more comprehensive and larger dataset for better analyzing the process and mechanisms

of friendship formation. Further, in addition to a stronger regard to nework structure and Blau’s

(1977) theorem on how majority and minority networks work, I suggest a shift of attention towards

the effect of social foci on tie formation among adolescents; namely, a differentiation between

homophily within one classroom (as a social focus) and homophily between classrooms; this

approach may have a higher chance in showing the significance of both social foci and homophily

in tie formation among adolescents. Additionally, regarding the unit of analysis, future studies

should focus on utilizing both the links and the individuals in analyzing social networks such as

schools to avoid the potential bias. Morevover, the significance of religious homophily among

Muslim students seems to need a closer look; that is, considering the fact that Muslim women are

more conspicuous than Muslim men (due to their hijab), it can be argued that Muslim women

become distinctive and that is why Muslim students’ friendship became statistically significant.

32

Since, due to lack of sufficient data, this argument could not be tested, in future research the

element of conspicuous religious elements should be taken into account.

Although understanding the process of tie formation in social networks are of significance, future

research should also concentrate on studying the consequences of strong homophilous relations in

any social contexts, especially in schools. Scholars should scrutinize the positive and negative

outcomes of a segregated adolescent social network.

8 Conclusion

In this research I studied the association between gender, religious, national/ethnic and political

homophily and the odds of being friends among adolescents in a high school. Further, I intended

to see the effect of network structure on homophilous relations according to distinctiveness

approach. The results showed that gender homophily is existent among high school students.

Religious homophily is not of important significance; except for Muslim students. Parents’

birthplace is an important factor in tie formation. Participating in political meetings is important

for friendship when it comes to political homophily.

Although the results of this research cannot be generalized to all of the adolescents living in

Stockholm, it sheds some light on some of the mechanisms at play in friendship formation.

33

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