Complex Contagions and the Diffusion of Innovations: Evidence from a Small-N Study

The recent literature on “complex contagions” challenges Granovetter’s classic hypothesis on the strength of weak ties and argues that, when the actors’ choice requires reinforcement from several sources, it is the structure of strong ties that really matters to sustain rapid and wide diffusion. The paper contributes to this debate by reporting on a small-N study that relies on a unique combination of ethnographic data, social network analysis, and computational models. In particular, we investigate two rural populations of Indian and Kenyan potters who have to decide whether to adopt new, objectively more efficient and economically more attractive, technical/stylistic options. Qualitative field data show that religious sub-communities within the Indian and Kenyan populations exhibit markedly different diffusion rates and speed over the last thirty years. To account for these differences, we first analyze empirically observed kinship networks and advice networks, and, then, we recreate the actual aggregate diffusion curves through a series of empirically calibrated agent-based simulations. Combining the two methods, we show that, while single exposure through heterophilious weak ties were sufficient to initiate the diffusion process, large bridges made of strong ties can in fact lead to faster or slower diffusion depending on the type of signals circulating in the network. We conclude that, even in presence of “complex contagions,” dense local ties cannot be regarded as a sufficient condition for faster diffusion.     

Book reviews

CHINA

CHARLOTTE FURTH. A Flourishing Yin: gender in China's Medical History, 960–1665. Berkeley: University of California Press, 1999. A Philip E. Lilienthal Book. xiv, 355 pp. 20 halftones, 13 line figures. US$45.00, hardcover; US$17.96, paper.

MOBO C. F. GAO. Gao Village. A Portrait of Rural Life in Modern China. London: C. Hurst & Company, 1999. xiv, 286 pp. Maps, illustrations, preface and acknowledgments, appendixes, index. £16.95, paper.

JAMES R. LILLEY and DAVID SHAMBAUGH (eds). China's Military Faces the Future. Armonk, NY: M. E. Sharpe, 1999. 368 pp. Illustrations, tables, graphs, index. US$74.95, hardcover; US$29.95, paper.

JAPAN, KOREA

MITSUHIRO YOSHIMOTO. Kurosawa: film Studies and Japanese Cinema. Durham NC: Duke University Press, 2000. 485 pp. Introduction, bibliography, index. US$64.95, hardcover; US$21.95, paper.

YASUNORI FUKUOKA (trans. Tom Gill). Lives of Young Ethnic Koreans in Japan. Melbourne: Trans Pacific Press, 2000. 300 pp. Introduction, tables, figures, notes, references, glossary, index. A$39.95, paper.

AH‐JEONG KIM and R. B. GRAVES (trans). The Metacultural Theater of Oh T'aeSok. Five Plays from the Korean Avant‐Garde. Honolulu: University of Hawai'i Press, 1999. 164 pp. Preface, introduction, translators' note, photographs, bibliography. US$33.00, hardcover; US$14.95, paper.

ANDREW COBBING. The Japanese Discovery of Victorian Britain: early Travel Encounters in the Far West. Surrey: Japan Library, 1998. 257 pp. Illustrations, preface, introduction, biographical appendix, notes and references, index. £45.00, hardcover.

SOUTH, WEST & CENTRAL ASIA

SATISH BALRAM AGNIHOTRI. Sex Ratio Patterns in the Indian Population: a Fresh Exploration. New Delhi: Sage Publications, 2000. 379 pp. Tables, figures, appendices, bibliography, index. Rs 475, hardcover.

SOUTHEAST ASIA

ROBERT CRIBB. Historical Atlas of Indonesia. Richmond: Curzon Press (in cooperation with the Nordic Institute for Asian Studies, Copenhagen), 2000. 256 pp. £75.00, hardcover.

STEFAN EKLOF. Indonesian Politics in Crisis: the Long Fall of Suharto, 1996–98. Copenhagen: Nordic Institute of Asian Studies, 1999. 288 pp. Introduction, bibliography, index. A$33.00, paper.

BARBARA LEIGH. The Changing Face of Malaysian Crafts: identity, Industry and Ingenuity. Kuala Lumpur: Oxford University Press, 2000. Glossary, bibliography, index. 124 pp. 59 colour and 92 b/w illustrations. A$85.00, hardcover.

KRISHNA SEN and DAVID T. HILL. Media, Culture and Politics in Indonesia. South Melbourne: Oxford University Press, 2000. 245 pp. A$35.00, paper.

GENERAL ASIA

DAVID HANLON and GEOFFREY M. WHITE (eds). Voyaging Through the Contemporary Pacific. Lanham, Boulder, New York, Oxford: Rowman & Littlefield Publishers, 2000. 443 pp. US$75.00, hardcover; US$24.95, paper.

LAKSIRIJAYASURIYAandKEEPOOKONG, (eds.) TheAsianisation ofAustralia?:someFacts about the Myths. Melbourne: Melbourne University Press, 1999. 114 pp. A$16.95, paper.     

Methods of Mapping and Identifying Small Clusters of Rare Diseases with Applications to Geographical Epidemiology

Geographical variation operates at a variety of scales. Methods of mapping variation in disease incidence between different countries or even counties are relatively well developed. When, however, the question relates to much smaller aggregations (that is, “clustering”), attention has mainly been restricted to areas near putative point hazards; the majority of cases are excluded from such an investigation. In this study we show how clustering may be investigated and displayed in such a way that it becomes a powerful tool in epidemiological research. As examples we use incidence data from the Yorkshire health region for selected childhood cancers and adult haematopoietic malignancies. The methods would readily extend to any small clusters of rare events.     

Ethnographic Clay Sourcing Practices: Insights for Archaeological Assemblage Interpretations

This paper uses examples of ethnographic clay sourcing strategies from coastal and central Kenyan communities (Digo, Jomvu, Chonyi, Tigania and Mbeere), and potsherds from the Manda archaeological site in Kenya (seventh-fourteenth centuries AD), to illustrate archaeological clay variability and discuss cultural and social behaviour which may contribute to paste inconsistences in an archaeological assemblage. I demonstrate that while function and environmental constraints influence the potters’ decision in the selection of clay sources/treatment, the choice may also be influenced by other factors such as aesthetics, which are dependent on the values of the customer, and in some cases, societal taboos. I also argue that clay sources are not always indicators of production centres, and that heterogeneity and homogeneity in paste composition could imply production centres and customer homesteads respectively.