Thomas W. Valente

Social network thresholds in the diffusion of innovations

Abstract Threshold models have been postulated as one explanation for the success or failure of collective action and the diffusion of innovations. The present paper creates a social network threshold model of the diffusion of innovations based on the Ryan and Gross (1943) adopter categories: (1) early adopters; (2) early majority; (3) late majority; (4) laggards. This new model uses social networks as a basis for adopter categorization, instead of solely relying on the system-level analysis used previously. The present paper argues that these four adopter categories can be created either with respect to the entire social system, or with respect to an individuals personal network. This dual typology is used to analyze three diffusion datasets to show how external influence and opinion leadership channel the diffusion of innovations. Network thresholds can be used (1) to vary the definition of behavioral contagion, (2) to predict the pattern of diffusion of innovations, and (3) to identify opinion leaders and followers in order to understand the two-step flow hypothesis better.

The stability of centrality measures when networks are sampled

The ability to measure centrality in social networks has been a particularly useful development in social network analysis. For researchers trying to decide which centrality measure is most meaningful and valid for their research purposes, various papers have explored the conceptual foundations of centrality measures. Less well documented is the empirical performance of centrality measures under different research scenarios or constraints. This study uses bootstrap sampling procedures to determine how sampling affects the stability of 11 different network centrality measures. Results indicate that some measures are more stable than others, and that stability is also a function of network and study properties.

Accelerating the Diffusion of Innovations Using Opinion Leaders

Theory on the diffusion of innovations has been used to study the spread of new ideas and practices for over 50 years in a wide variety of settings. Most studies have been retrospective, and most have neglected to collect information on interpersonal communication networks. In addition, few have attempted to use the lessons from diffusion research to accelerate the diffusion of innovations. This article outlines a method to accelerate the diffusion of innovations using opinion leaders. The authors present their optimal matching procedure and report on computer simulations that show how much faster diffusion occurs when initiated by opinion leaders. Limitations and extensions of the model are discussed.

Identifying Opinion Leaders to Promote Behavior Change

This article reviews 10 techniques used to identify opinion leaders to promote behavior change. Opinion leaders can act as gatekeepers for interventions, help change social norms, and accelerate behavior change. Few studies document the manner in which opinion leaders are identified, recruited, and trained to promote health. The authors categorize close to 200 studies that have studied or used opinion leaders to promote behavior change into 10 different methods. They present the advantages and disadvantages of the 10 opinion leader identification methods and provide sample instruments for each. Factors that might influence programs to select one or another method are then discussed, and the article closes with a discussion of combining and comparing methods.

TYPE II TRANSLATION Transporting Prevention Interventions From Research to Real-World Settings

This article summarizes research on Type II translation of prevention interventions aimed at enhancing the adoption of effective programs and practices in communities. The primary goal of Type II translation is to institutionalize evidence-based programs, products, and services. First, the authors describe theoretical frameworks that are useful to guide Type II translation research. Second, research on prevention program implementation, including fidelity of implementation and factors that are associated with successful program implementation, is summarized. The authors describe interventions designed to enhance the dissemination of preventive interventions in community and public health settings. Third, they describe strategies used by prevention program developers who have taken programs to scale. Fourth, they present a case example of Project Towards No Drug Abuse (TND), an empirically validated high school–based substance abuse prevention program. They describe ongoing research on the dissemination of Project TND. Finally, they provide suggestions for future Type II translation research.

Effects of a Social-Network Method for Group Assignment Strategies on Peer-Led Tobacco Prevention Programs in Schools

OBJECTIVES Our study tested the effectiveness of network methods for identifying opinion leaders and for constructing groups. METHODS Three conditions-random, teacher, and network--ere randomly assigned to 84 6th-grade classrooms within 16 schools. Pre- and postcurriculum data on mediators of tobacco use were collected from 1961 students. Peer leaders in the network condition were identified by student nominations, and those leaders were matched with the students who nominated them. RESULTS Students in the network condition relative to the random condition liked the prevention program more and had improved attitudes (beta = -0.06; P <.01), improved self-efficacy (beta = -0.10; P <.001), and decreased intention to smoke (adjusted odds ratio [OR] = 0.46; 95% confidence interval [CI] = 0.38, 0.55). CONCLUSIONS The network method was the most effective way to structure the program. Future programs may refine this technique and use it in other settings.

Social network associations with contraceptive use among Cameroonian women in voluntary associations.

This paper examines the association between social networks and contraceptive use. Using data from a survey of women belonging to voluntary associations in Yaoundé, Cameroon, we find that the behavior and characteristics of the members of a respondents personal networks are associated with her contraceptive use, over and above a set of her own individual characteristics that are usually found to be important. Respondents who report that their network partners approve of contraception, use it, and encourage the respondent to use are more likely to use contraception themselves; the association with encouragement is particularly strong. Moreover, there is a strong association between the specific methods of contraception used by a respondent and those used by her network partners, suggesting that members of personal networks exchange and evaluate specific methods. Because most of the respondents network partners were interviewed, we are able to compare the respondents perceptions of contraceptive use by her network partners with the network partners actual use. We find that it is perceptions of use that matter, even if those perception are incorrect.

Translation in the Health Professions Converting Science into Action

The systematic translation of evidence-based research findings, tools, and information into practice is critical to improving the quality of our nation’s health. However, despite several decades of advances in developing medical knowledge based on high-quality empirical evidence, widespread implementation of these findings into practice in diverse applied settings has not been achieved. This article reviews definitions and conceptual models that describe the translation of research from basic discovery to real-world applications, summarizes the various issues involved in the process of translation, discusses multiple barriers, and provides recommendations to surmount these hurdles. Areas of further research in this arena are suggested. Finally, the article concludes that translational research is an important area to continue to pursue requiring long-term collaborative commitment among researchers and practitioners.

Using Social Networks to Understand and Prevent Substance Use: A Transdisciplinary Perspective

We review findings from research on smoking, alcohol, and other drug use, which show that the network approach is instructive for understanding social influences on substance use. A hypothetical network is used throughout to illustrate different network findings and provide a short glossary of terms. We then describe how network analysis can be used to design more effective prevention programs and to monitor and evaluate these programs. The article closes with a discussion of the inherent transdisciplinarity of social network analysis.

Adolescent Affiliations and Adiposity: A Social Network Analysis of Friendships and Obesity

Friendship choices and BMI were measured for 617 adolescents 11-15 years of age. Overweight youth were twice as likely to have overweight friends. There was a weak association between social position and weight status. Overweight youth nominated more friends but were nominated as friends less frequently than their normal weight peers.