Table 1.

Definitions of constructs related to social relations

Construct	Description	Reference (all reviewed in Wang et al., 2017 [19])
Loneliness	A painful subjective emotional state occurring when there is a discrepancy between desired and achieved patterns of social interaction.	Hawkley & Cacioppo, 2009; Peplau & Perlman, 1982
Social isolation	Inadequate quality and quantity of social relations with other people at the individual, group, community, and larger social environment levels where human interaction takes place.	Zavaleta, Samuel & Mills, 2014
Social support	Structural social support: the existence, quantity, and properties of an individual’s social relations; it focuses on the study of structural aspects of social contacts, such as the characteristics of the support network. Functional social support: the functions fulfilled by social relations, such as emotional support which involves caring, love and empathy; instrumental support (referred to by many as tangible support); informational support which consists of information, guidance or feedback that can provide a solution to a problem; appraisal support which involves information relevant to self-evaluation and social companionship, which involves spending time with others in leisure and recreational activities.	Cohen & Hoberman, 1983; House 1981; Moreno, 2004; Wills, 1985
Social network	A specific set of linkages among a defined set of persons, with the additional property that the characteristics of these linkages as a whole may be used to interpret the social behaviour of the persons involved: Size: the number of people with whom the respondent has had social contact e.g. in the last month; Frequency of contact: the number of people with whom the respondent has had social contact e.g. daily; weekly; or monthly over the past month; Density: the proportion of all possible ties between network members which are present (i.e., how many of a respondent’s network know each other); Proportion of kin/non-kin in social network: How many of the total number of people within a respondent’s social network are relatives?; Intensity: whether relationships are “uniplex” (one function only) or “multiplex” (more than one function); Directionality: who is helping whom in a dyadic relationship.	Cohen & Sokolovsky, 1978; Mitchell, 1969
Individual social capital	A series of resources that individuals earn as a result of their membership in social networks, and the features of those networks that facilitate coordination and cooperation for mutual benefit; can be understood as the property of an individual. Most commonly measured by asking individuals about their participation in social relationships (such as membership of groups) and their perceptions of the quality of those relationships.	De Silva, McKenzie, Harpham & Huttly, 2005; McKenzie, Whitley & Weich, 2002; Portes, 1998; Putnam, 2000
Confiding relationships	The number of people with whom the respondent reports they can talk about worries or feelings.	Brown & Harris, 1978; Murphy, 1982