Exploring variation in active network size: Constraints and ego characteristics

Studies of active personal networks have primarily focused on providing reliable estimates of the size of the network. In this study, we examine how compositional properties of the network and ego characteristics are related to variation in network size. There was a negative relationship between mean emotional closeness and network size, for both related and unrelated networks. Further, there was a distinct upper bound on total network size. These results suggest that there are constraints both on the absolute number of individuals that ego can maintain in the network, and also on the emotional intensity of the relationships that ego can maintain with those individuals.     

Social network characteristics associated with risky behaviors among runaway and homeless youth.

Runaway and homeless youth are at high risk for substance abuse and unsafe sexual behavior. Our study describes the personal social networks of these youth and examines network characteristics associated with risky behaviors. In 1995 and 1996, we interviewed a purposive sample of youth aged 14 through 21 who were living in Washington, DC and were identified on the streets or through shelters or other service agencies (N = 327). Although we found that most youth reported current social relationships, a significant minority (26%) did not. Youth without a social network were significantly more likely to report current illicit drug use, multiple sex partners, and survival sex than youth with a network. For youth with a network, the networks were small, strong in affective and supportive qualities, comprised primarily of friends, typically included an alcohol or illicit drug user, and usually were not a source of pressure for risky behaviors. Our results indicate that networks had risk-enhancing and risk-decreasing properties in that network characteristics were associated in both positive and negative directions with risky behaviors.     

Unpacking Burt’s constraint measure

Burt (1992) proposed two principal measures of structural holes, effective size and constraint. However, the formulas describing the measures are somewhat opaque and have led to a certain amount of confusion. Borgatti (1997) showed that, for binary data, the effective size formula could be written very simply as degree (ego network size) minus average degree of alters within the ego network. The present paper presents an analogous reformulation of the constraint measure. We also derive minima and maxima for constraint, showing that, for small ego networks, constraint can be larger than one, and for larger ego networks, constraint cannot get as large as one. We also show that for networks with more than seven alters, the maximum constraint does not occur in a maximally dense or closed network, but rather in a relatively sparse “shadow ego network”, which is a network that contains an alter (the shadow ego) that is connected to every other alter, and where no other alter-alter ties exist.     

The Game of Contacts: Estimating the Social Visibility of Groups

Estimating the sizes of hard-to-count populations is a challenging and important problem that occurs frequently in social science, public health, and public policy. This problem is particularly pressing in HIV/AIDS research because estimates of the sizes of the most at-risk populations-illicit drug users, men who have sex with men, and sex workers-are needed for designing, evaluating, and funding programs to curb the spread of the disease. A promising new approach in this area is the network scale-up method, which uses information about the personal networks of respondents to make population size estimates. However, if the target population has low social visibility, as is likely to be the case in HIV/AIDS research, scale-up estimates will be too low. In this paper we develop a game-like activity that we call the game of contacts in order to estimate the social visibility of groups, and report results from a study of heavy drug users in Curitiba, Brazil (n = 294). The game produced estimates of social visibility that were consistent with qualitative expectations but of surprising magnitude. Further, a number of checks suggest that the data are high-quality. While motivated by the specific problem of population size estimation, our method could be used by researchers more broadly and adds to long-standing efforts to combine the richness of social network analysis with the power and scale of sample surveys.     

Linked Ego Networks: Improving estimate reliability and validity with respondent-driven sampling

Respondent-driven sampling (RDS) is currently widely used for the study of HIV/AIDS-related high risk populations. However, recent studies have shown that traditional RDS methods are likely to generate large variances and may be severely biased since the assumptions behind RDS are seldom fully met in real life. To improve estimation in RDS studies, we propose a new method to generate estimates with ego network data, which is collected by asking respondents about the composition of their personal networks, such as “what proportion of your friends are married?”. By simulations on an extracted real-world social network of gay men as well as on artificial networks with varying structural properties, we show that the precision of estimates for population characteristics is greatly improved. The proposed estimator shows superior advantages over traditional RDS estimators, and most importantly, the method exhibits strong robustness to the recruitment preference of respondents and degree reporting error, which commonly happen in RDS practice and may generate large estimate biases and errors for traditional RDS estimators. The positive results henceforth encourage researchers to collect ego network data for variables of interests by RDS, for both hard-to-access populations and general populations when random sampling is not applicable.     

Network stability in longitudinal data: A case study from rural Malawi

This paper investigates the stability of egocentric informal conversational networks in rural Malawi by analyzing reinterview data collected by a longitudinal survey. Contrary to the findings of test–retest studies carried out in developed countries, in rural Malawi geographically and socially close networks are found to exhibit a low level of stability even over short periods of time. This is mainly attributed to the specific structure of the networks considered, and it is therefore recommended that the importance of measurement bias should not be overemphasized. It is also found that, despite the significant changes in the named partners, network size and reported actions of network partners are quite stable, thus suggesting a negligible impact of network instability for further analyses of these data.     

Longitudinal Associations Between Other‐Sex Friendships and Substance Use in Adolescence

The impact of the changes in the gender composition of friendship networks during early adolescence on substance use in late adolescence was examined. The hypothesis was that initial level and increase in the proportion of other‐sex friends in the network would be associated with higher levels of substance use among girls, but not among boys. Girls and boys (n=390) were interviewed annually from ages 12 to 18 (79% retention). For both boys and girls, initial level in the proportion of other‐sex friends predicted alcohol use in late adolescence, whereas it was predictive of drug use in girls only. Moreover, for girls only, a faster increase in the proportion of other‐sex friends in the network predicted later use of alcohol and drugs.     

Estimating network structure via random sampling: Cognitive social structures and the adaptive threshold method

This paper introduces and tests a novel methodology for measuring networks. Rather than collecting data to observe a network or several networks in full, which is typically costly or impossible, we randomly sample a portion of individuals in the network and estimate the network based on the sampled individuals’ perceptions on all possible ties. We find the methodology produces accurate estimates of social structure and network level indices in five different datasets. In order to illustrate the performance of our approach we compare its results with the traditional roster and ego network methods of data collection. Across all five datasets, our methodology outperforms these standard social network data collection methods. We offer ideas on applications of our methodology, and find it especially promising in cross-network settings.     

Network cohesion and social support

This article analyses the effects of personal network cohesion on different types of social support using two dimensions of cohesion: network closure (defined as a tightly knit set of actors around the ego) and cliquishness (defined as the extent to which an actor is connected with a number of cohesive sub-sets of alters). Data were obtained from a personal networks’ survey conducted in Catalonia (Spain), which was completed by 441 adults and gathered information about exchange of social support in networks made of 30 alters. A multilevel analysis disentangles the effects on support of these two structural dimensions at the network-level from compositional effects at the network and tie-level. The results show that network closure does not play a relevant role in support once confounders at the network and tie levels are controlled for. However, cliquishness has a significant association with labor-related support and housing support, net of statistical controls. Implications of these results in network research are discussed.     

At the intersection of criminal justice involvement and sexual orientation: Dynamic networks and health among a population-based sample of young Black men who have sex with men

Mass incarceration of young Black men has a significant impact on their network composition and stability that, in turn, may have major implications for health and well-being. A sub-group of young Black men with criminal justice involvement (CJI) identify as gay, bisexual or are non-identified men who have sex with men (hereafter MSM). This paper focuses on the potential effects of CJI on the composition of Black MSM social and sexual networks, their stability over time, and concomitant health and social outcomes. We use data from the UConnect study, a population-based cohort of young Black MSM 16–29 years of age (n = 618) selected using respondent-driven sampling in Chicago from 2013 to 2016. Both confidant and sexual network name generators and interpreters were administered at 9-month intervals over three waves of data collection. Ego and dyadic-level data were collected on behaviors prevalent among MSM and including factors associated with network CJI, network stability, and health outcomes. Generalized Structural Equation Models (GSEM) were utilized to determine the relationship between CJI network composition, network stability and behaviors prevalent among young Black MSM and their networks. In the UConnect cohort, 46% had at least once been detained, arrested or spent time in jail or prison. In addition, 20% of participants reported incident CJI over the study period. Respondents with a history of CJI were significantly more likely to have CJI homophily in their confidant and sexual networks. Multivariate analyses demonstrate that the association between one’s history of CJI, housing instability and drug use is partially explained by one’s network CJI. In addition, a higher prevalence of network CJI is associated with increased turnover in the confidant network, and this network instability is also related to important health and social outcomes. This analysis describes the networks of criminal justice involved men among a representative sample of young Black MSM and demonstrates the relationship between CJI network homophily, network stability and their impact on several key health and social outcomes relevant to this population.     

Predictors of Sexual Behavior Among Early and Middle Adolescents Affected by Maternal HIV

ABSTRACT. We describe the extent to which men who have sex with men and women (MSMW) tell their female sex partners that they have male sex partners and the association between disclosure of male partners and condom use with female partners. Data were from U.S. Internet-using MSMW recruited from a social networking Web site. Of 666 MSMW, 70% told their last female partner that they had male sex partners. MSMW who disclosed having male sex partners were equally likely to have used a condom during their last vaginal intercourse with a female partner (42%) as were men who did not disclose (47%). Because disclosure was not associated with condom use and condom use was low, it is important to continue efforts to promote consistent condom use, especially among females, regardless of the reported sexual orientation of their partners.     

A sexual affiliation network of swingers,heterosexuals practicing risk behaviours that potentiate the spread of sexually transmitted infections: A two-mode approach

Using the example of the sexual affiliation networks of swingers, this paper examines how the analysis of sexual affiliation networks can contribute to the development of sexually transmitted infection (STI) prevention strategies. Two-mode network methodology and ERGMs are applied to describe the structural composition of the affiliation network and analyse attribute effects. Swingers were found to recruit their sex partners through one large, moderately cohesive network component. Swingers who used drugs or had a longer history of swinging tended to frequent websites instead of clubs. This study confirms the relevance of studying sexual affiliation networks and its additional value for STI epidemiology.     

Small networks and selectivity bias in the analysis of survey network data

Selectivity bias is a danger whenever observations are systematically excluded from a data set on the basis of a dependent variable, whether this exclusion is explicit or implicit. If present, the problem has severe consequences for the validity of statistical estimates of effects. The problem is of importance to the analysis of survey network data, since many network measures (such as density) are available only for persons having networks of size two or larger, while others (such as percent kin) are defined only for those having networks of size one or more. Analysts can adjust for selectivity bias by estimating the risk of exclusion (in this case, of having a network of size 0 or 1), and including the modeled risk as a control in substantive equations. Such estimates are presented for the 1985 General Social Survey network data; in the course of this results of Fischer and Phillips on social isolation are replicated. Other ways of guarding against selection bias are also discussed; at a minimum, network size should be included among the set of regressors in analyses of survey network data, as a methodological control if not as a substantive variable.     

Temporal Relationship of Sex Risk Behaviors and Substance Use Severity Among Men in Substance Use Treatment

Sex risk behaviors and substance use are intertwined. Many men continue to engage in high-risk sexual behaviors even when enrolled in substance use disorder (SUD) treatment. We hypothesized that changes in sex risk behaviors would coincide with changes in drug/alcohol use severity among men in SUD treatment. During an HIV risk-reduction trial, men in methadone maintenance and outpatient drug-free treatment (N = 359) completed assessments at baseline and six months after. We assessed changes in sex risk and substance use severity, using the Addiction Severity Index–Lite (ASI-Lite), controlling for treatment condition. In multinomial logistic regressions, decreased alcohol severity was significantly associated with decreases in reported sex partners, and increased alcohol severity was significantly associated with increases in reported sex partners. Increasing drug use severity was significantly associated with maintaining and initiating sex with a high-risk partner, while decreasing alcohol use severity was significantly associated with discontinuing sex under the influence. However, changes in drug/alcohol use severity were not associated with changes in unprotected sex. Substance use reductions may decrease HIV risk behaviors among male substance users. Our findings highlight the importance of integrating interventions in SUD treatment settings that address the intersection of sex risk behaviors and substance use.     

A Communication Perspective on Video Lottery Terminals

Video Lottery Terminals (VLT) are associated with pathological gambling and with most of the requests for help in combating gambling addiction. Embeddedness of a person in his or her social network is among the communicational factors that may help explain this phenomenon. To verify this, we compared ego networks of VLT gamblers, of gamblers of games with low request for help and of VLT gamblers in treatment (n = 90). The networks of regular VLT gamblers are small and dense and offer little social support. Gamblers in treatment also have small networks, but they are less dense, have more components and offer more social support. Networks of gamblers with low requests for assistance are approximately twice the size as those of VLT gamblers, are sparser and offer more companionship. In conclusion, the VLT gambler is not an isolated individual, but rather an individual ‘shut-in’ a small network of tightly knitted relationships.     

Duocentered networks

When a pair of individuals is central to a research problem (e.g., husband and wife, PhD student and supervisor) the concept of “duocentered” networks can be defined as a useful extension of egocentered networks. This new structure consists of a pair of central egos and their direct links with alters, instead of just one central ego as in the egocentered networks or multiple egos as in complete networks. The key point in this kind of network is that ties exist between the central pair of egos and between them and all alters, but the ties among alters are not considered. Duocentered networks can also be considered as a compromise between egocentered and complete networks. Complete network measurements are often costly to obtain and tend to contain a large proportion of missing data (especially for peripheral actors). Egocentered network data are less costly but a lot of information is lost with their use when a pair of individuals is the relevant unit of analysis.     

Considering clustering measures: Third ties,means, and triplets

Measures that estimate the clustering coefficients of ego and overall social networks are important to social network studies. Existing measures differ in how they define and estimate triplet clustering with implications for how network theoretic properties are reflected. In this paper, we propose a novel definition of triplet clustering for weighted and undirected social networks that explicitly considers the relative strength of the tie connecting the two alters of the ego in the triplet. We argue that our proposed definition better reflects theorized effects of the important third tie in the social network literature. We also develop new methods for estimating triplet, local and global clustering. Three different types of mathematical means, i.e. arithmetic, geometric, and quadratic, are used to reflect alternative theoretical assumptions concerning the marginal effect of tie substitution.     

Experiments in the measurement of the size of social networks

This paper reports the results of a series of experiments conducted to measure the effects of alternative procedures for determining the size of social networks. The three methods tested are recall, recognition, and numerical estimation. Respondents were selected from work, church, and social groups. The major findings were that recall estimates are substantially below those obtained by recognition methods and become worse for larger groups. On average, numerical estimates are reasonable approximations of network size estimates based on recognition, but there is substantial variability in the accuracy of individual reports. Surprisingly, there is no evidence that recall is better for reports on number of close friends than of friends or acquaintances. There are order effects on numerical estimates of network size and better estimates are obtained by first asking about close friends. Finally, there is some evidence that respondent characteristics such as age affect recall of network size.     

Sexual Risk Behavior Among Women with Injected Drug Use Histories

This study documents the sexual risk, behavior for HIV infection and transmission in inner-city women with a history of injected drug use (IDU). The sample consists of N = 38 HIV+ and N = 37 HIV- women who were demographically comparable. A surprisingly high number of women in both. groups reported both male and female sex partners during their lifetime, and significantly more HIV+ women currently identified as bisexual and lesbian. Overall, HIV+ women had had more lifetime male and female sex partners, although the two groups did not differ in their current sexual behavior regarding numbers of partners and sex occasions. Both groups of women had little information about risk characteristics of their male sex partners, except for a history of IDU that was common among partners of both HIV+ and HIV- women. Sex for money was practiced by a subgroup of women in both groups and sex in exchange for drugs by very few women. A disturbingly high number of HIV+ and HIV- women reported occasions of unprotected sex during the past six months (86% vs. 97%), a finding that suggests that educational efforts for behavior change in IDU women need to be intensified.     

Structural holes and bridging in two-mode networks

Social networks are often structured in such a way that there are gaps, or “structural holes,” between regions. Some actors are in the position to bridge or span these gaps, giving rise to individual advantages relating to brokerage, gatekeeping, access to non-redundant contacts, and control over network flows. The most widely used measures of a given actor’s bridging potential gauge the extent to which that actor is directly connected to others who are otherwise not well connected to each other. Unfortunately, the measures that have been developed to identify structural holes cannot be adapted directly to two-mode networks, like individual-to-organization networks. In two-mode networks, direct contacts cannot be directly connected to each other by definition, making the calculation of redundancy, effective size, and constraint impossible with conventional one-mode methods. We therefore describe a new framework for the measurement of bridging in two-mode networks that hinges on the mathematical concept of the intersection of sets. An actor in a given node class (“ego”) has bridging potential to the extent that s/he is connected to actors in the opposite node class that have unique profiles of connections to actors in ego’s own node class. We review the relevant literature pertaining to structural holes in two-mode networks, and we compare our primary bridging measure (effective size) to measures of bridging that result when using one-mode projections of two-mode data. We demonstrate the results of applying our approach to empirical data on the organizational affiliations of elites in a large U.S. city.