This text presents a key to understanding how ideas, products and opinions ""take off"" and spread throughout society - referred to as the diffusion of innovation - and provides a means to estimate how fast or slow that spread occurs. The diffusion of innovations occurs among individuals in a social system, and the pattern of communications among these individuals is a social network. The network determines how quickly innovations diffuse and the timing of each individual's adoption. The book thus analyses how social networks structure the diffusion of innovation. Chapter 1 reviews the diffusion of innovation theory, network analysis, and the datasets used as examples. Chapter 2 reviews prior research conducted on threshold and critical mass models. Chapter 3 presents relational network models of diffusion which posit that individuals adopt innovations based on their direct relations with others in their social system, and the next chapter provides structural network models of diffusion which posit that individuals adopt innovations based on their position in the social system, regardless of direct ties to specific others. Threshold and critical mass models of diffusion are presented in chapters 5 and 6. Chapter 7 develops a general threshold model of adoption based on social networks. This book is addressed to researchers, policymakers and students interested in diffusion of innovation or network analysis. It is also meant for those interested in studying the process of social change as represented by a diffusion network paradigm. Finally, individuals interested in developing, evaluating or understanding communication campaigns and media effects can use these concepts to improve their work.
Part 1 Introduction: Diffusion of Innovations and Network Analysis; Diffusion Versus Collective Behaviour; Datasets Analysed; Contagion. Part 2 Prior Research on Thresholds and the Critical Mass: Epidemiology; Geography; Markets and Economics; Collective Behaviour; Interactive Communication Technologies; Public Opinion; Decay Processes; Subgroups. Part 3 Relational Diffusion Networks: Opinion Leadership; Group Membership; Personal Network Density; Personal Network Exposure. Part 4 Structural Diffusion Networks: The Strength of Weak Ties; Centrality; Positional Equivalence; Structural Equivalence; Relational vs. Structural. Part 5 Threshold Models of Diffusion: Threshold Models; Network Thresholds; Personal Network Exposure; Threshold Lags; Structural Network Thresholds. Part 6 Critical Mass Models of Diffusion: Inflection Points; Structural Measures of the Critical Mass; Finding Critical Mass; Testing Critical Mass Definitions. Part 7 Empirical Analyses of Threshold Models: Micro- and Macrolevels of Analysis; Adopted Categories; A Threshold/Critical Mass (T/CM) Model. Part 8 Other Network Models and Methods: Other Threshold Models; Corrected Thresholds; Event History Analysis; Complementarity; Dyads. Part 9 Conclusions and Discussions: Applications; Contrasting Network Thresholds with the Classic Diffusion Model; Conclusions; Limitations; Future Research.
