Although social capital has been researched from many approaches and attempts have been made to measure it online, the literature lacks an operational description that would allow its measurement criteria to be established from a social network perspective. Therefore, the purpose of this paper is to identify in the literature what metrics researchers use to measure Social Capital on social networking sites from a social network perspective. Thus, this contribution offers a theoretical description of the key elements for measuring social capital in social networking sites, which may be useful in subsequent studies
The social dimension of sustainability refers to the ability to maintain society in a certain state that is affected by the social structure, interaction, norms, values, and shared language that contribute to social well-being [7
]. Different factors have been suggested to describe the social implications of sustainability, among them one of the most important is social capital (i.e., [10
]), which is the focus of this study as a non-physical contributing factor of social sustainability.
In the scientific literature, social capital has become increasingly important in the discourse on ties for building and social interaction on social networking sites (SNS). There is evidence that creating and strengthening ties in a social network generates identifiable social capital and that this capital contributes to economic growth and development based on the construction of mutually satisfactory relationships [12
A commonly identified weakness in research on social capital in the SNS is its measurement [15
]. Firstly, there is a lack of coherence between the multiple theoretical definitions of social capital and in specifying its main components. Secondly, there is no operational description of the key elements for assessing social capital with data from the SNS and no agreed set of indicators [18
2. Theoretical Background
2.1. Social Dimension of Sustainability
Sustainability is a widely used term with a wide range of definitions and has become a multi-focal agenda. Since 1987, it has been interpreted as a continuous process of development in which environmental, economic, ethical, and social considerations are integrated to meet the needs of a community. These dimensions are conceived as separate and independently connected. Although there is a constant flow of resources between them, their boundaries are diffuse, especially those of the social dimension. This is perhaps because its impact is easily identifiable as the dimension that affects the other dimensions of sustainability, but it is not easily measurable [10
In the 1990s, this dimension had been neglected, playing a minor role in sustainability discussions compared to the other dimensions. However, in the last decades, it has been considered as a fundamental aspect within the sustainability agenda even though its notion remains under-theorized, with some lack of connection to the other dimensions and difficulties in recording it empirically [20
The social dimension of sustainability is a process for the creation, consolidation, and maintenance of a prosperous society that provides for common well-being and needs. On the one hand, it is determined by physical (i.e., social infrastructure) and non-physical (i.e., social capital) factors [11
]. On the other hand, it is affected by the social structure, its characteristics, and what happens within it in terms of norms, values, and interactions.
Social capital describes, systematically, social interaction and social networks, conceiving them as integral aspects. Hence, some authors associate social capital as a component of sustainability, among others, that contribute to the satisfaction of needs that change regularly in a society [9
]. Therefore, this study focuses on breaking down the concept of social capital to the point of presenting a measurement framework of its different dimensions based on the indicators of the network perspective: specifically, when resource transfer and ties occur in SNS platforms.
2.2. Social Capital
Social capital has been studied in different fields of social, economic, and political science [28
], creating a large number of definitions and representations of its characteristics. Various researchers, from Hanifan [29
] to Adler and Kwon [18
], have distinguished social capital according to context, forms, possible uses, and interaction groups [7
]; however, the concept that has been most widely accepted and applied is that proposed by Bourdieu [37
“Social capital is the aggregate of the actual or potential resources which are linked to possession of a durable network of more or less institutionalized relationships of mutual acquaintance and recognition, which provides each of its members with the backing of the collectively-owned capital, a “credential” which entitles them to credit, in the various senses of the word”.
The social capital available to members of a group is integrated into their social networks and represents an investment in relationships for future profit [7
]. Membership, network connections, and close interaction provide access to these resources, allowing them to improve their quantity, quality, depth, and efficiency of exchange by promoting the consecutive development of an individual or a community [17
In short, beyond the information or resources directly held by one member, the importance of social capital lies in the set of resources—economic, cultural, or symbolic—of other members that can be mobilized thanks to their relationships and connections [38
]. The social capital available depends on the social context, the position that each member has in the network, its connections, and the level of access.
2.3. Categorizing Social Capital from Two Approaches
Two main points of view are identified in the study of social capital: one is centered on the social structure represented in the ties inherent in the relations [7
], and the other is based on the typology of the resources mobilized in the relations of material or symbolic exchange [30
The first approach, strongly influenced by network theory, analyzes the nature of social capital from the type of ties between its sources and highlights the theory of the strength of weak ties [43
] and Burt’s structural holes [45
]. The second approach analyzes the nature of social capital from its effects as proposed by Nahapiet and Ghoshal [32
], Tsai and Ghoshal [36
], among others. Thus, these two approaches enable social capital to be categorized according to the type of ties and the type of resources ().
Table 1. Framework of the definition and characterization of social capital (own elaboration) *.
“The sum of resources, actual or potential, that correspond to an individual through the possession of a lasting social network based on good relationships” 
|Type of ties
Exclusive relationships—favors trust and social support
Dense and cohesive network structures
No lack of ties
Mobilizing new information
Suitable for dissemination
Facilitate greater exchange
Large social structures
Absence of ties
||Network configuration and position
||Shared values and interests
||Social relationship behaviors
3. Operationalization of Social Capital
Although there is general agreement on what social capital is, what creates it, and what it provides, its measurement has been made difficult mainly by the variety of theoretical perspectives that have not provided for the definition of concrete indicators or their operational feasibility [73
]. In particular, contextualizing social capital from the perspective of social networks enables the observation and progressive measurement of the increase in members’ resources when the capacity of access and exchange increases within the network [147
]. However, their operationalization and testing have currently proved to be a maze [161
], resulting in a variety of non-unified approaches.
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