Master of Arts / Department of Sociology, Anthropology, and Social Work / Dana M. Britton / The literature on friendship and social networks finds that individuals form social ties with people who are like them; this is termed "homophily." Several researchers demonstrate that social networks and social ties are homophilous with regard to race and class, for example. However, few studies have explored the relationship of homophily to the social ties of lesbians, and fewer still have explicitly examined sexual orientation as a point of homophily. This study intends to help fill that gap by looking at homophily among lesbian social ties, as well as how urban and non-urban residency might shape homophily and lesbian social ties. I gathered data that would answer the following central research questions: Are lesbian social ties homophilous and if so around what common characteristics? What are lesbians' experiences with community resources and how does this influence their social ties? How does population influence lesbian social ties? Data for this research come from 544 responses to an internet survey that asked lesbians about their social ties, their interests and activities and those of their friends, and the cities or towns in which they resided. Using the concepts of status and value homophily, I attempt to make visible some of the factors and forces that shape social ties for lesbians.

Thesis advisor: Utku Unver / This dissertation is composed of three essays in microeconomic theory. The first and second essays are in the theory of matching, with hierarchical organizations and complementarities being their respective topic. The third essay is in on electoral competition and political polarization as a result of manipulation of public opinion through social influence networks. Hierarchies are a common organizational structure in institutions. In the first essay, I offer an explanation of this fact from a matching-theoretic perspective, which emphasizes the importance of stable outcomes for the persistence of organizational structures. I study the matching of individuals (talents) via contracts with institutions, which are aggregate market actors, each composed of decision makers (divisions) enjoined by an institutional governance structure. Conflicts over contracts between divisions of an institution are resolved by the institutional governance structure, whereas conflicts between divisions across institutions are resolved by talents' preferences. Stable market outcomes exist whenever institutional governance is hierarchical and divisions consider contracts to be bilaterally substitutable. In contrast, when governance in institutions is non-hierarchical, stable outcomes may not exist. Since market stability does not provide an impetus for reorganization, the persistence of markets with hierarchical institutions can thus be rationalized. Hierarchies in institutions also have the attractive incentive property that in a take-it-or-leave-it bargaining game with talents making offers to institutions, the choice problem for divisions is straightforward and realized market outcomes are pairwise stable, and stable when divisions have substitutable preferences. Complementarity has proved to be a challenge for matching theory, because the core and group stable matchings may fail to exist. Less well understood is the more basic notion of pairwise stability. In a second essay, I define a class of complementarity, asymmetric complements, and show that pairwise stable matchings are guaranteed to exist in matching markets where no firm considers workers to be asymmetric complements. The lattice structure of the pairwise stable matchings, familiar from the matching theory with substitutes, does not survive in this more general domain. The simultaneous-offer and sequential-offer versions of the worker-proposing deferred acceptance algorithm can produce different matchings when workers are not necessarily substitutable. If no firm considers workers to be imperfect complements, then the simultaneous-offer version produces a pairwise stable matching, but this is not necessarily true otherwise. If no firm considers workers to be asymmetric complements, a weaker restriction than no imperfect complements, then the sequential-offer version produces a pairwise stable matching, though the matching produced is order-dependent. In a third essay, I examine electoral competition in which two candidates compete through policy and persuasion, and using a tractable two-dimensional framework with social learning provide an explanation for increasing political polarization. Voters and candidates have policy preferences that depend upon the state of the world, which is known to candidates but not known to voters, and are connected through a social influence network that determines through a learning process the final opinion of voters, where the voters' initial opinions and the persuasion efforts of the candidates affect final opinions, and so voting behavior. Equilibrium level of polarization in policy and opinion (of both party and population) increases when persuasion costs decrease. An increase in homophily increases the equilibrium level of policy polarization and population opinion polarization. These comparative static results help explain the increased polarization in both the policy and opinion dimensions in the United States. / Thesis (PhD) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

Background: The advice and opinions given by consumers online have been proven to have a positive influence on consumers purchase intentions. It has previously been established by researchers that consumer-created information is more trustworthy compared to information provided by a seller. As a result, consumers’ eWOM has taken over the stage on the internet. Social media has in comparison to traditional media brought communication to a new level in terms of engaging consumers online. For instance, bloggers nowadays are assumed to be viewed as peers that can generates social ties between a blogger and a blog reader due to a blogger’s credibility. Thus, the power of peer communication is of relevance when considering persuasion in real life as well as online. Purpose: The purpose of this study is to examine how eWOM can be a powerful tool through social ties between the source and the receiver when it comes to generating consumers’ purchase intentions. The authors intend to contribute with an understanding of how different sociodemographic factors of homophily and source credibility can potentially have a direct or indirect influence on the persuasion process online. To understand the process of how consumers are persuaded through eWOM the authors examine the relationship between Swedish blog readers and Swedish bloggers and the process of how the readers are absorbing and using the bloggers’ message. Methodology & Method: This study was conducted using a qualitative methodology approach. The primary data was collected through interviews and observations. Ten interviews were implemented on the selected sample consisting of women living in Sweden, who are in the ages of 16-25 and read famous Swedish lifestyle blogs. Furthermore, the favourite blogs of the interviewees were observed by the researchers in order to complement the interviews. Conclusion: From this research the authors have found that homophily creates social ties between the blog reader and the blogger, and therefore this underpins that the likelihood of persuasion is higher if several factors of homophily exists. However, the factors of homophily are not sufficient on its own to establish a relationship between eWOM and purchase intentions. Rather, source credibility is considered to be the major factor that determines the extent of purchase intentions.

Syfte med uppsatsen är att ta reda på om ungdomar efter diskussioner kring politiska och samhälleliga frågor påverkar varandras åsikter och blir mer lika. Studien baseras på enkätsvar från gymnasieelever som följts från årskurs ett i gymnasiet till årskurs två från tre skolor i Örebro. Totalt deltog 1688 elever i denna longitudinella studie. Multipel regressionsanalys visade att ungdomarna påverkar varandra men deras åsikter blev inte mer lika varandra över tid och att det fanns en svag skillnad mellan könen. Diskussionen tar upp hur dessa resultat skiljer sig ifrån befintliga studier på området och indikerar att "politik" är ett abstrakt ämne som vid diskussion skiljer sig från andra diskussionsämnen.

This study looked at how individuals choose whom to work with when a task necessitates collaboration. Prior research done on collaborative environments as well as outcomes of collaboration suggests that who you collaborate with will depend on two primary factors: the individuals from which you have to choose and the circumstances surrounding the task. In the proposed study, these factors will be explored. This thesis identified the lack of literature on informal collaboration, addressing the gap in the literature regarding processes that individuals use when choosing collaborators. This research focused on the influencing factors of similarity and expertise involved in this decision processes. Furthermore, this study aimed to understand how individuals choose collaborators under differing conditions of difficulty, novelty, and interdependence necessitated by the task.

As online shopping continues to grow rapidly, research indicates its massive uptake can be the result of the integration of social media technologies within the e-commerce interface. This has been further exacerbated by the COVID-19 pandemic which has led to an acceleration in the use of e-commerce. However, despite the growing popularity of e-commerce, shopping online is characterized by high levels of uncertainty given the spatial and temporal separation between consumer and vendor. This presents a dire impact on a consumer’s decision-making process and can specifically impact a consumer’s decision confidence. Decision confidence is an important construct that has been shown to be central in influencing a consumer’s behaviour, specifically in regards to purchase-related activities. Few studies have shed light on the factors influencing a consumer’s decision confidence in the e-commerce context. Online shopping platforms fitted with social data markers are able to gauge and track the activities and attributes of online consumers, providing convenient heuristics on various measures such as the total number of recommendations for a product, or the degree of similarity between consumers. These markers may facilitate group identification through the development of herd behaviour. Herd behaviour arises in situations of uncertainty and motivates individuals to identify with a group (herd), and conform to its actions. Various aspects of a herd can influence group identification. This research focuses on two aspects of herd behaviour in e-commerce environments: homophily and herd size. Homophily is the degree to which individuals are similar, and in this study, we examine homophily from the perspective of an individual and the herd to which they may be exposed to. Herd size is the number of individuals in a group taking a specific action such as an online purchase decision. Drawing on the social identity approach and uncertainty identity theory, this investigation hones in on how homophily and herd size arise in the e-commerce context, and examines how group identification through homophily and herd size may reduce uncertainty and build decision confidence through the formation of trust, entitativity, sense of community and information helpfulness. A research model is developed along with a set of supported hypotheses. An online experiment utilizing a hypothetical e-commerce website was conducted with 400 participants. The results were analyzed using structural equation modeling and choice-based conjoint analysis. The results suggest that while homophily significantly impacts trust, sense of community, entitativity and information helpfulness, herd size does not. The results also suggest that whereas trust, sense of community and information helpfulness positively impact decision confidence, entitativity does not. It was also empirically demonstrated that participants preferred measures of homophily in the e-commerce interface more than measures of herd size. Furthermore, it was demonstrated that participants preferred measures indicating homophily in interests and demographics more than information on either alone, and that information on homophily in interests was more preferred than information on homophily in demographics. / Dissertation / Doctor of Philosophy (PhD) / Despite the rapid uptake in e-commerce, shopping online continues to be characterized by high levels of uncertainty given the spatial and temporal separation between consumer and vendor. This uncertainty negatively impacts a consumer’s decision confidence, which is a key driver in influencing consumer behaviour. Drawing on the social identity approach and uncertainty identity theory, this study investigates how elements of the e-commerce interface can facilitate group identification, a process which has been empirically demonstrated to reduce uncertainty and thereby increase decision confidence. Findings of this study suggest that measures of homophily embedded within an e-commerce platform can work through various mediators to facilitate group membership which can positively impact a consumer’s decision confidence. Theoretical and practical contributions of this study are discussed for researchers, academics, and practitioners wishing to explore those aspects of online shopping that an aid the decision-making process through group-related processes.

This thesis contributes to a better understanding of social media designs for more civil conversations online. I first demonstrated that people disengage from social media interactions when they encounter uncivil behavior from friends. To find alternative designs for social media that are more civil, I evaluated novel social interaction techniques. To do this, I designed a six-phase framework for prototyping social interactions called piggyback prototyping; and an algorithmic probe study methodology to include participants in the development of social curation algorithms. I built a piggyback prototype that modifies the civility on Facebook by highlighting positive posts in green and hiding impolite posts, and I deployed it as an algorithmic probe with 20 participants. I uncovered ways to improve the algorithm, and I found that participants responded most favorably to having civil posts highlighted. These findings open avenues for future research in designing pro-social platforms.

People always find themselves interacting with others and forming ties with them; these ties shape an individual’s social network which helps 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 be significant; political homophily was only significant 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 of the adolescents living in Stockholm. However, this research sheds some light on the mechanisms at play in friendship formation among adolescents.

In this thesis I investigate the effects of positive and negative connections on social and organization networks, and the presence and role of homophily in networks of scientific collaborations and citations through the combination of methodologies borrowed from complexity science, statistics, and organizational sciences. In the first part of the thesis, I study the differences between patterns of positive and negative connections among individuals in two online signed social networks. Findings suggest that the sign of links in a social network shapes differently the network's topology: there is a positive correlation between the degrees of two nodes, when they share a positive connection, and a negative correlation when they share a negative connection. I then move my focus to the study of a dataset on start-ups from which I construct and analyse the competition and mobility networks among companies. Results show that the presence of competition has negative effects on the mobility of people among companies and on the success of the start-up ecosystem of a nation. Competitive behaviours may also emerge in science. Therefore, in the second part of this thesis, I focus on a database of all papers and authors who have published in the American Physical Society (APS) journals. Through the analysis of the citation network of the APS, I propose a method that aims to statistically validate the presence (or absence) of a citation between any two articles. Results show that homophily is an important mechanism behind the citation between articles: the more two articles share similar bibliographies, i.e., deal with similar arguments, the more likely there is a citation between them. In the last chapter, I investigate the presence of homophily in the APS data set, this time at the level of the collaboration network among sci- entists. Results show that homophily can be responsible in fostering collaboration, but above a given point the effect of similarity decreases the probability of a collaboration. Additionally, I propose a model that successfully reproduces the empirical findings.

This quantitative study considers homophily and inclusion in the secondary agriculture classroom. This study uses social identity and homophily theories to examine classroom culture and how homophily and inclusion impact it. The study aims to use demographic questions and homophily scales to determine whether homophily is occurring in the secondary agriculture classroom and to what extent. This study also uses social distance scales to determine the breaking point or how willing seniors in an agriculture class are to include new students based on the bi-variables of Race, Sexuality, and Social subgroup. The results indicate that homophily and in-group mentality is occurring within Kentucky’s secondary agricultural education classrooms.