Fixed choice design and augmented fixed choice design for network data with missing observations.

The statistical analysis of social networks is increasingly used to understand social processes and patterns. The association between social relationships and individual behaviors is of particular interest to sociologists, psychologists, and public health researchers. Several recent network studies make use of the fixed choice design (FCD), which induces missing edges in the network data. Because of the complex dependence structure inherent in networks, missing data can pose very difficult problems for valid statistical inference. In this article, we introduce novel methods for accounting for the FCD censoring and introduce a new survey design, which we call the augmented fixed choice design (AFCD). The AFCD adds considerable information to analyses without unduly burdening the survey respondent, resulting in improvements over the FCD, and other existing estimators. We demonstrate this new method through simulation studies and an analysis of alcohol use in a network of undergraduate students living in a residence hall.

Identification and Description of Potentially Influential Social Network Members using the Strategic Player Approach.

Background: Diffusion of innovations theory posits that ideas and behaviors can be spread through social network ties. In intervention work, intervening upon certain network members may lead to intervention effects "diffusing" into the network to affect the behavior of network members who did not receive the intervention. The strategic players (SP) method, an extension of Borgatti's Key Players approach, is used to balance the (sometimes) opposing goals of spreading the intervention to as many members of the target group as possible, while preventing the spread of the intervention to others. Objectives: We sought to test whether members of the SP set have network position and non-network differences (such as demographic, attitudinal, or behavioral differences) compared to the remaining members of the target group (non-SPs). Methods: A first-year class at a private residential university (N = 1342) completed network and non-network measures. Analyses were restricted only to heavy drinkers, leading to a final analytic sample of 529. Results: SPs and non-SPs differed on multiple network variables, but did not differ on most demographic, attitudinal, and behavior variables. Conclusions: As designed, the SP program identified participants who were distinguished by their network position. The fact that they did not also differ on other characteristics shows the SPs are not significantly different than heavy drinkers who were not selected.

Minority Stressors Associated with Sexual Risk Behaviors and HIV Testing in a U.S. Sample of Transgender Individuals.

The majority of published research on transgender health focuses on associations between external minority stressors (e.g., discrimination) and health. Little is known about how internal minority stressors (e.g., identity concealment and expecting rejection) might predict HIV disparities. The current study addresses this gap by examining the association between external and internal minority stressors and sexual risk behaviors and HIV testing history in a sample of 300 transgender adults across the U.S. Transgender-related discrimination and expecting rejection were associated with sexual risk behaviors. When controlling for covariates, none of the minority stressors were associated with HIV testing. Results illustrate how minority stress, both external and internal, may operate uniquely for transgender individuals.

Strategic Players for Identifying Optimal Social Network Intervention Subjects.

We present a method whereby social network ties are used to identify behavioral leaders who are situated in the network such that these individuals are: 1) able to influence other individuals who are in need of and most receptive to intervention, thereby maximizing the impact of the intervention; and 2) not embedded with ties that are likely to be behaviorally antagonistic to the intervention or that would compromise the optimal evaluation of intervention efficacy. In this study we developed a novel method which we call Strategic Players, which is a solution for identifying a set of players who are close to a target subset of the network (i.e., the targeted group), and far away from the subset we wish to avoid (i.e. the avoidance group). This solution seeks to maximize the diffusion of the behavior to the targeted group while minimizing contact and influence from the avoidance group. We apply this method to two different social networks.

Distinct Coping Profiles Are Associated With Mental Health Differences in Transgender and Gender Nonconforming Adults.

OBJECTIVE: This study assessed the unique coping strategies of transgender and gender nonconforming (TGNC) individuals in the United States used to manage gender-related stress, and examined associations between specific coping profiles and mental health. METHODS: Data were from 316 participants in the 2014-2015 Transgender Stress and Health Study, an online study of TGNC mental and sexual health. A factor analysis of the coping measure (Brief COPE) was followed by a k-means cluster analysis to evaluate distinct profiles of coping with gender-related stress. Proportional odds models and logistic regression models indicated how coping profiles related to levels of self-reported depressive symptoms and suicidality. RESULTS: A 4-factor structure was identified with three distinct profiles of coping with gender-related stress, each representative of the frequency (high or low) in which participants used functional and dysfunctional coping strategies: (a) high-functional/low-dysfunctional, (b) high-functional/high-dysfunctional, and (c) low-functional/low-dysfunctional. There were significant differences in depressive symptoms and suicidality based on distinct gender-related coping profiles. The high-functional/high-dysfunctional group reported significantly poorer mental health compared with the high-functional/low-dysfunctional group. CONCLUSION: To improve mental health outcomes in TGNC individuals, health providers and researchers should strive to not only promote functional coping strategies for managing gender-related stress but also decrease dysfunctional coping strategies.

Advance care planning as a shared endeavor: completion of ACP documents in a multidisciplinary cancer program.

OBJECTIVE: We examined the roles of oncology providers in advance care planning (ACP) delivery in the context of a multidisciplinary cancer program. METHODS: Semi-structured interviews were conducted with 200 women with recurrent and/or metastatic breast or gynecologic cancer. Participants were asked to name providers they deemed important in their cancer care and whether they had discussed and/or completed ACP documentation. Evidence of ACP documentation was obtained from chart reviews. RESULTS: Fifty percent of participants self-reported completing an advance directive (AD) and 48.5% had named a healthcare power of attorney (HPA), 38.5% had completed both, and 39.0% had completed neither document. Among women who self-reported completion of the documents, only 24.0% and 14.4% of women respectively had documentation of an AD and HPA in their chart. Completion of an AD was associated with number (adjusted odds ratio [AOR] = 1.49) and percentage (AOR = 6.58) of providers with whom the participant had a conversation about end-of-life decisions. Participants who named a social worker or nurse practitioner were more likely to report having completed an AD. Participants who named at least one provider in common (e.g., named the same oncologist) were more likely to have comparable behaviors related to naming a HPA (AOR = 1.13, p = 0.011) and completion of an AD (AOR = 1.06, p = 0.114). CONCLUSIONS: Despite the important role of physicians in facilitating ACP discussions, involvement of other staff was associated with a greater likelihood of completion of ACP documentation. Patients may benefit from opportunities to discuss ACP with multiple members of their cancer care team. Copyright © 2015 John Wiley & Sons, Ltd.

Bayesian Peer Calibration with Application to Alcohol Use.

Peers are often able to provide important additional information to supplement self-reported behavioral measures. The study motivating this work collected data on alcohol in a social network formed by college students living in a freshman dormitory. By using two imperfect sources of information (self-reported and peer-reported alcohol consumption), rather than solely self-reports or peer-reports, we are able to gain insight into alcohol consumption on both the population and the individual level, as well as information on the discrepancy of individual peer-reports. We develop a novel Bayesian comparative calibration model for continuous, count, and binary outcomes that uses covariate information to characterize the joint distribution of both self and peer-reports on the network for estimating peer-reporting discrepancies in network surveys, and apply this to the data for fully Bayesian inference. We use this model to understand the effects of covariates on both drinking behavior and peer-reporting discrepancies. Copyright © 2016 John Wiley & Sons, Ltd.

Dynamic social network analysis of a brief alcohol intervention trial in heavy-drinking college students shows spillover effects.

BACKGROUND: Heavy-drinking college students tend to have close social networks, and there is theoretical and empirical support for the idea that behavior change can spread through those networks via close ties. The objective of this research was to determine whether intervention-induced behavior change in a subset of heavy drinkers in a sociometric (whole) college class-year social network is transmitted to other heavy drinkers in the network, resulting in reduced behavioral risk and change in network ties. METHODS: We conducted a controlled trial in which most of a first-year college class (N = 1236; 56.9% female) was enrolled, with alcohol use and social network ties measured early in each of three semesters. Following a baseline assessment, the network was divided into two groups, brief motivational intervention (BMI) and natural history control (NHC) according to dormitory residence location. A subset of heavy drinkers in each group was selected, and those in the BMI group received an in-person intervention. RESULTS: Using stochastic actor-oriented modeling, we found a significant tendency for participants in the BMI group to shed ties with individuals with similar drinking behaviors between the first and second semesters, relative to the NHC group. Furthermore, heavy drinkers with reciprocal ties to intervention recipients in the BMI group showed a significant reduction in drinks per week. CONCLUSIONS: Individual alcohol interventions appear to have effects both on behavior and network connections among individuals who did not receive the intervention. Continued research is needed to identify the optimal conditions for the diffusion of behavior change.

Social Networks and Sexual and Gender Minority Disparities in Alcohol Use and Consequences Among First-Year College Students.

Purpose: In this work, we investigate the association between social relationships and alcohol use and the related consequences of sexual and gender minority (SGM) college students, and we highlight the importance of SGM social networks as a potential protective factor among SGM college students. Methods: The study used data from 1340 students (47.2% White and non-Hispanic, 55.4% assigned female at birth, 16.3% SGM), which were collected during the 2016 fall semester of the first year of college at one university. The study collected information about alcohol use and related consequences and about the social networks of participants through a peer nomination survey. Results: Regardless of SGM status, students who nominated at least one SGM peer reported significantly lower drinks per week (ß = -0.69, p = 0.04) and heavy drinking frequency (ß = -0.38, p = 0.02) after adjusting for relevant covariates including peer drinking. SGM participants showed a significantly stronger negative association between having an SGM peer and heavy drinking frequency and alcohol-related consequences than their cisgender heterosexual counterparts (ß = -0.90, p = 0.04; ß = -1.32, p = 0.03). Conclusion: These findings highlight the importance of SGM social networks as a potential protective factor for reducing alcohol use and related consequences among SGM college students. College campuses should identify ways to support connections among SGM students. Clinical trials registration number is NCT02895984.

Durability of Protection Post-Primary COVID-19 Vaccination in the United States.

The durability of immune responses after COVID-19 vaccination will drive long-term vaccine effectiveness across settings and may differ by vaccine type. To determine durability of protection of COVID-19 vaccines (BNT162b2, mRNA-1273, and Ad26.COV2.S) following primary vaccination in the United States, a matched case-control study was conducted in three cohorts between 1 January and 7 September 2021 using de-identified data from a database covering 168 million lives. Odds ratios (ORs) for developing outcomes of interest (breakthrough SARS-CoV-2 infection, hospitalization, or intensive care unit admission) were determined for each vaccine (no direct comparisons). In total, 17,017,435 individuals were identified. Relative to the baseline, stable protection was observed for Ad26.COV2.S against infections (OR [95% confidence interval (CI)], 1.31 [1.18-1.47]) and hospitalizations (OR [95% CI], 1.25 [0.86-1.80]). Relative to the baseline, protection waned over time against infections for BNT162b2 (OR [95% CI], 2.20 [2.01-2.40]) and mRNA-1273 (OR [95% CI], 2.07 [1.87-2.29]) and against hospitalizations for BNT162b2 (OR [95% CI], 2.38 [1.79-3.17]). Baseline protection remained stable for intensive care unit admissions for all three vaccines. Calculated baseline VE was consistent with published literature. This study suggests that the three vaccines in three separate populations may have different durability profiles.

Stability and change in self-reported sexual orientation identity in young people: application of mobility metrics.

This study investigated stability and change in self-reported sexual orientation identity over time in youth. We describe gender- and age-related changes in sexual orientation identity from early adolescence through emerging adulthood in 13,840 youth ages 12-25 employing mobility measure M, a measure we modified from its original application for econometrics. Using prospective data from a large, ongoing cohort of U.S. adolescents, we examined mobility in sexual orientation identity in youth with up to four waves of data. Ten percent of males and 20% of females at some point described themselves as a sexual minority, while 2% of both males and females reported ever being "unsure" of their orientation. Two novel findings emerged regarding gender and mobility: (1) Although mobility scores were quite low for the full cohort, females reported significantly higher mobility than did males. (2) As expected, for sexual minorities, mobility scores were appreciably higher than for the full cohort; however, the gender difference appeared to be eliminated, indicating that changing reported sexual orientation identity throughout adolescence occurred at a similar rate in female and male sexual minorities. In addition, we found that, of those who described themselves as "unsure" of their orientation identity at any point, 66% identified as completely heterosexual at other reports and never went on to describe themselves as a sexual minority. Age was positively associated with endorsing a sexual-minority orientation identity. We discuss substantive and methodological implications of our findings for understanding development of sexual orientation identity in young people.

The influence of peer and parental norms on first-generation college students' binge drinking trajectories.

INTRODUCTION: First-generation college students are those whose parents have not completed a four-year college degree. The current study addressed the lack of research on first-generation college students' alcohol use by comparing the binge drinking trajectories of first-generation and continuing-generation students over their first three semesters. The dynamic influence of peer and parental social norms on students' binge drinking frequencies were also examined. METHODS: 1342 college students (n = 225 first-generation) at one private University completed online surveys. Group differences were examined at Time 1, and latent growth-curve models tested the association between first-generation status and social norms (peer descriptive, peer injunctive, parental injunctive) on binge drinking trajectories. RESULTS: Overall, binge drinking frequency tended to decline over the first three semesters of college. After controlling for demographics, substance-free dormitory residence, parental alcohol problems and norms, first-generation status was associated with steeper declines in binge drinking frequency. During the first semester, the association between parental injunctive norms and binge drinking frequency was stronger for first-generation students than for continuing-generation students; this influence declined over time for first-generation students. The influence of peer descriptive norms on binge drinking increased for continuing-generation students; while this influence remained stable over time for first-generation students. CONCLUSIONS: First-generation student status appears to be protective against binge drinking. Substance-free dormitory residence, and perceived parental and peer norms likely play a role in first-generation students' tendency to engage in binge drinking less often over the first year of college.

Do misperceptions of peer drinking influence personal drinking behavior? Results from a complete social network of first-year college students.

This study considered the influence of misperceptions of typical versus self-identified important peers' heavy drinking on personal heavy drinking intentions and frequency utilizing data from a complete social network of college students. The study sample included data from 1,313 students (44% male, 57% White, 15% Hispanic/Latinx) collected during the fall and spring semesters of their freshman year. Students provided perceived heavy drinking frequency for a typical student peer and up to 10 identified important peers. Personal past-month heavy drinking frequency was assessed for all participants at both time points. By comparing actual with perceived heavy drinking frequencies, measures of misperceptions of heavy drinking (accurately estimate, overestimate, underestimate) were constructed for both general and important peers. These misperceptions were then used as predictors of concurrent and prospective personal heavy drinking frequency and intentions using network autocorrelation analyses. The majority of students (84.8%) overestimated, 11.3% accurately estimated, and 3.9% underestimated heavy drinking among their general peers, whereas 42.0% accurately estimated, 36.9% overestimated, and 21.1% underestimated important peers' heavy drinking. For both referents, overestimation of peer heavy drinking was associated with more frequent heavy drinking and higher drinking intentions at both time points. Importantly, the effects of underestimating and overestimating close peers' drinking on personal alcohol use were significant after controlling for the influence of misperceptions of general peers' heavy drinking. Close peers are a critical referent group in assessments related to social norms for young adult alcohol use. Implications for prevention and intervention are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Enrollment and assessment of a first-year college class social network for a controlled trial of the indirect effect of a brief motivational intervention.

Heavy drinking and its consequences among college students represent a serious public health problem, and peer social networks are a robust predictor of drinking-related risk behaviors. In a recent trial, we administered a Brief Motivational Intervention (BMI) to a small number of first-year college students to assess the indirect effects of the intervention on peers not receiving the intervention. OBJECTIVES: To present the research design, describe the methods used to successfully enroll a high proportion of a first-year college class network, and document participant characteristics. METHODS: Prior to study enrollment, we consulted with a student advisory group and campus stakeholders to aid in the development of study-related procedures. Enrollment and baseline procedures were completed in the first six weeks of the academic semester. Surveys assessed demographics, alcohol use, and social network ties. Individuals were assigned to a BMI or control group according to their dormitory location. RESULTS: The majority of incoming first-year students (1342/1660; 81%) were enrolled (55% female, 52% nonwhite, mean age 18.6 [SD = 0.51]). Differences between the intervention and control group were noted in alcohol use, but were in large part a function of there being more substance-free dormitory floors in the control group. CONCLUSIONS: The current study was successful in enrolling a large proportion of a first-year college class and can serve as a template for social network investigations.

U.S. College Students' Social Network Characteristics and Perceived Social Exclusion: A Comparison Between Drinkers and Nondrinkers Based on Past-Month Alcohol Use.

OBJECTIVE: There is a general perception on college campuses that alcohol use is normative. However, nondrinking students account for 40% of the U.S. college population. With much of the literature focusing on intervening among drinkers, there has been less of a focus on understanding the nondrinker college experience. The current study has two aims: to describe the social network differences between nondrinkers and drinkers in a college setting, and to assess perceived social exclusion among nondrinkers. METHOD: First-year U.S. college students (n = 1,342; 55.3% female; 47.7% non-Hispanic White) were participants in a larger study examining a social network of one college class and network associations with alcohol use. Alcohol use, sociocentric and egocentric network ties were assessed, as were experiences of social exclusion related to nondrinking. RESULTS: Drinking homophily based on past-month use was found; students tended to associate with others with a similar drinking status. Compared with drinkers, nondrinkers received fewer network nominations within the first-year network and made more nominations outside the first-year network. Nondrinkers' perceived social exclusion was positively related to the number of drinkers in their social networks, such that those with more drinkers in their network reported more social exclusion. CONCLUSIONS: College students' past-month drinking status in the first semester of college is related to their network position and perception of social exclusion. Nondrinking students who are part of a nondrinking community are less likely to feel socially excluded. Improving our understanding of the nondrinker college experience should improve support services for these students.

Relationships between social network characteristics, alcohol use, and alcohol-related consequences in a large network of first-year college students: How do peer drinking norms fit in?

A burgeoning area of research is using social network analysis to investigate college students' substance use behaviors. However, little research has incorporated students' perceived peer drinking norms into these analyses. The present study investigated the association between social network characteristics, alcohol use, and alcohol-related consequences among first-year college students (N = 1,342; 81% of the first-year class) at one university. The moderating role of descriptive norms was also examined. Network characteristics and descriptive norms were derived from participants' nominations of up to 10 other students who were important to them; individual network characteristics included popularity (indegree), network expansiveness (outdegree), relationship reciprocity, and network density. Descriptive norms were defined as participants' average perceived binge drinking frequency among their nominated peers. Network autocorrelation models revealed that indegree and descriptive norms were positively associated with participants' average number of drinks per week, binge drinking frequency, and alcohol-related consequences. Indegree and outdegree interacted with descriptive norms, such that when participants perceived less frequent binge drinking among their peers, outdegree was associated with less alcohol consumption but not consequences. When participants perceived more frequent binge drinking among their peers, indegree and outdegree were associated with more alcohol consumption but not consequences. The present results suggest that being popular and believing that heavy episodic drinking is normative among one's peers are associated with greater alcohol risk. Further, alcohol risks associated with nominating more peers may be enhanced or lessened depending on students' peer drinking norms. Implications for future research and interventions are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

An event- and network-level analysis of college students' maximum drinking day.

BACKGROUND: Heavy episodic drinking is common among college students and remains a serious public health issue. Previous event-level research among college students has examined behaviors and individual-level characteristics that drive consumption and related consequences but often ignores the social network of people with whom these heavy drinking episodes occur. The main aim of the current study was to investigate the network of social connections between drinkers on their heaviest drinking occasions. METHODS: Sociocentric network methods were used to collect information from individuals in the first-year class (N=1342) at one university. Past-month drinkers (N=972) reported on the characteristics of their heaviest drinking occasion in the past month and indicated who else among their network connections was present during this occasion. RESULTS: Average max drinking day indegree, or the total number of times a participant was nominated as being present on another students' heaviest drinking occasion, was 2.50 (SD=2.05). Network autocorrelation models indicated that max drinking day indegree (e.g., popularity on heaviest drinking occassions) and peers' number of drinks on their own maximum drinking occasions were significantly associated with participant maximum number of drinks, after controlling for demographic variables, pregaming, and global network indegree (e.g., popularity in the entire first-year class). CONCLUSION: Being present at other peers' heaviest drinking occasions is associated with greater drinking quantities on one's own heaviest drinking occasion. These findings suggest the potential for interventions that target peer influences within close social networks of drinkers.

Resistance to peer influence moderates the relationship between perceived (but not actual) peer norms and binge drinking in a college student social network.

INTRODUCTION: Adolescent and young adult binge drinking is strongly associated with perceived social norms and the drinking behavior that occurs within peer networks. The extent to which an individual is influenced by the behavior of others may depend upon that individual's resistance to peer influence (RPI). METHODS: Students in their first semester of college (N=1323; 54.7% female, 57% White, 15.1% Hispanic) reported on their own binge drinking, and the perceived binge drinking of up to 10 important peers in the first-year class. Using network autocorrelation models, we investigated cross-sectional relationships between participant's binge drinking frequency and the perceived and actual binge drinking frequency of important peers. We then tested the moderating role of RPI, expecting that greater RPI would weaken the relationship between perceived and actual peer binge drinking on participant binge drinking. RESULTS: Perceived and actual peer binge drinking were statistically significant predictors of participant binge drinking frequency in the past month, after controlling for covariates. RPI significantly moderated the association between perceptions of peer binge drinking and participant's own binge drinking; this association was weaker among participants with higher RPI compared to those with lower RPI. RPI did not interact with the actual binge drinking behavior of network peers. CONCLUSIONS: RPI may function to protect individuals from the effect of their perceptions about the binge drinking of peers, but not from the effect of the actual binge drinking of peers.

Alcohol perceptions and behavior in a residential peer social network.

Personalized normative feedback is a recommended component of alcohol interventions targeting college students. However, normative data are commonly collected through campus-based surveys, not through actual participant-referent relationships. In the present investigation, we examined how misperceptions of residence hall peers, both overall using a global question and those designated as important peers using person-specific questions, were related to students' personal drinking behaviors. Participants were 108 students (88% freshman, 54% White, 51% female) residing in a single campus residence hall. Participants completed an online baseline survey in which they reported their own alcohol use and perceptions of peer alcohol use using both an individual peer network measure and a global peer perception measure of their residential peers. We employed network autocorrelation models, which account for the inherent correlation between observations, to test hypotheses. Overall, participants accurately perceived the drinking of nominated friends but overestimated the drinking of residential peers. Consistent with hypotheses, overestimating nominated friend and global residential peer drinking predicted higher personal drinking, although perception of nominated peers was a stronger predictor. Interaction analyses showed that the relationship between global misperception and participant self-reported drinking was significant for heavy drinkers, but not non-heavy drinkers. The current findings explicate how student perceptions of peer drinking within an established social network influence drinking behaviors, which may be used to enhance the effectiveness of normative feedback interventions.

The relevance of network prominence and reciprocity of relationships for alcohol use and alcohol-related problems in a college residence hall network.

Peer associations are influential for substance use among college students, but relatively few investigations have been conducted on the social network characteristics that are associated with problematic alcohol use in college. This study investigated the association between network characteristics of prestige, expansiveness, and reciprocity and alcohol use variables in a college residence hall network. Undergraduate students in 1 residence hall (N = 129; 51.9% female; 48.1% non-Hispanic White; 84.5% first-year) reported on their alcohol use and alcohol-related problems in the past semester and nominated up to 10 residence hall peers who were important to them. Network autocorrelation modeling evaluated the association between 5 network variables reflecting prestige (indegree and betweenness centrality), expansiveness (outdegree), and relationship agreement (indegree reciprocity and outdegree reciprocity) and 3 indicators of alcohol use (drinks per week, number of heavy drinking days, number of alcohol problems). Moderation by gender of the associations between network characteristics and alcohol variables was also investigated. Models controlled for demographics and network autocorrelation. A higher outdegree and higher betweenness centrality within the residence hall network were significantly related to the number of heavy drinking days and number of alcohol problems, respectively. Higher indegree and higher betweenness centrality were associated with more alcohol problems for women when alcohol use was controlled. Having higher prestige and indicating oneself as having more friends in a college residential network may convey alcohol-related risks, with some risks higher for women.