Book reviews

Diffusion Processes and Fertility Transition: Selected Perspectives. 2001. Edited by John B. Caster-Line. National Research Council, Committee on Population. Washington, DC: National Academies Press. Pp. xi + 271. N.p.g. ISBN: 0-309-07610-2. Available online at http://www.nap.edu/books/0309076102/html/Rl.html The Explanatory Power of Models. 2002. Edited by Robert Franck. Boston/Dordrecht/London: Kluwer Academic Publishers. Pp. x + 310. ￡74.00. ISBN: 1-4020-0867-8. Communism, Health and Lifestyle. The Paradox of Mortality Transition in Albania, 1950-1990. 2001. By Arjan Gjon?a. Westport, CT: Greenwood Press. Pp. ix + 227. US$69.95. ISBN: 0-313-31586-8. Historical Studies in Mortality Decline. 2002. By William H. Hubbard, Kari Pitk?nen, Jürgen Schlumbohm, S?lvi Sogner, Gunnar Thorvaldsen, and Frans van Poppel. Oslo: Novus Forlag. Pp. 134. ISBN: 82-7099-360-3. Population and Society in Western European Port-Cities. 2002. Edited by Richard Lawton and Robert Lee. Liverpool: Liverpool University Press. Pp. xx + 385. ￡18.95. ISBN: 0-85323-907-X. The Changing Face of Home: The Transnational Lives of the Second Generation. 2003. Edited by Peggy Levitt and Mary C. Waters. New York: Russell Sage Foundation. Pp. xi + 408. US$39.95. ISBN: 0-87154-517-9. The Demography of Victorian England and Wales. 2000. By Robert Woods. Cambridge: Cambridge University Press. Pp. xxv + 447. ￡50.00. ISBN: 0-521-78254-6. The Life Table: Modelling Survival and Death. 2002. Edited by Guillaume Wunsch, Michel Mouchart, and Josianne Duchêne. Dordrecht: Kluwer Academic Publishers (European Studies of Population, Volume 11). Pp. x + 306. ￡89.00. ISBN: 1-4020-0638-1.     

Pricing of American options in discrete time using least squares estimates with complexity penalties

Pricing of American options in discrete time is considered, where the option is allowed to be based on several underlying stocks. It is assumed that the price processes of the underlying stocks are given by Markov processes. We use the Monte Carlo approach to generate artificial sample paths of these price processes, and then we use nonparametric regression estimates to estimate from this data so-called continuation values, which are defined as mean values of the American option for given values of the underlying stocks at time t subject to the constraint that the option is not exercised at time t. As nonparametric regression estimates we use least squares estimates with complexity penalties, which include as special cases least squares spline estimates, least squares neural networks, smoothing splines and orthogonal series estimates. General results concerning rate of convergence are presented and applied to derive results for the special cases mentioned above. Furthermore the pricing of American options is illustrated by simulated data.     

Birth month,school graduation,and the timing of births and marriages

We investigated the timing of fertility and marriage in Sweden using exogenous variation in the age at school graduation that results from differences in birth month. Our analysis found that the difference of 11 months in the age at leaving school between women who were born in two consecutive months, December and January, implies a delay in the age at first birth of 4.9 months. This effect of delayed graduation also persists for the timing of second births and first marriages, but it does not affect completed fertility or the overall probability of marriage before age 45. These results suggest the existence of a relatively rigid sequencing of demographic events in early adulthood, and the age at graduation from school emerges as an important factor in determining the timing--but not the quantum--of familyformation. In addition, these effects point to a potentially important influence of social age, defined by an individual's school cohort, instead of biological age. The relevance of social age is likely due to social interactions and peer-group influences exerted by individuals who are in the same school cohort but are not necessarily of the same age.     

The Popular Debate about Low Fertility: An Analysis of the German Press, 1993–2001

Despite increasing research on the causes, consequences, and measurement of low fertility, questions about the nature and the extent of popular concerns over low fertility have yielded more speculation than examination. We address this gap in the literature through an analysis of 328 German newspaper and news magazine articles mentioning low fertility from 1993 to 2001. Our analysis reveals a paradox: while fertility rates have remained well below replacement levels and governmental discussions of low fertility have increased, discussion of low fertility as a concern in and of itself has been small and unchanging over time. We find this to be true because the problem of low fertility is rarely invoked as a concern in its own right, but is most often used as a tool in the popular debate to discuss other problems – political, economic, and cultural.     

Social networks and changes in contraceptive use over time: evidence from a longitudinal study in rural Kenya

The impacts of social networks on changes in contraception in rural Kenya are investigated using special data from a longitudinal household survey. An analytic model, informed by detailed knowledge of the setting, yielded estimates that indicate that (1) social networks have substantial effects even after unobserved factors (e.g., homophily) that may determine social networks are controlled; (2) controlling for these unobserved factors may substantially alter the estimated effects of networks (these controls were not used in previous studies); (3) network effects are important for both men and women; and (4) network effects are nonlinear and asymmetric, suggesting that networks provide information primarily through social learning, rather than by exerting social influence.     

Health Selection,Migration, and HIV Infection in Malawi

Despite its importance in studies of migrant health, selectivity of migrants—also known as migration health selection—has seldom been examined in sub-Saharan Africa (SSA). This neglect is problematic because several features of the context in which migration occurs in SSA—very high levels of HIV, in particular—differ from contextual features in regions that have been studied more thoroughly. To address this important gap, we use longitudinal panel data from Malawi to examine whether migrants differ from nonmigrants in pre-migration health, assessed via SF-12 measures of mental and physical health. In addition to overall health selection, we focus on three more-specific factors that may affect the relationship between migration and health: (1) whether migration health selection differs by destination (rural-rural, rural-town, and rural-urban), (2) whether HIV infection moderates the relationship between migration and health, and (3) whether circular migrants differ in pre-migration health status. We find evidence of the healthy migrant phenomenon in Malawi, where physically healthier individuals are more likely to move. This relationship varies by migration destination, with healthier rural migrants moving to urban and other rural areas. We also find interactions between HIV-infected status and health: HIV-infected women moving to cities are physically healthier than their nonmigrant counterparts.     

Social networks and HIV/AIDS risk perceptions

Understanding the determinants of individuals' perceptions of their risk of becoming infected with HIV and their perceptions of acceptable strategies of prevention is an essential step toward curtailing the spread of this disease. We focus in this article on learning and decision-making about AIDS in the context of high uncertainty about the disease and appropriate behavioral responses. We argue that social interactions are important for both. Using longitudinal survey data from rural Kenya and Malawi, we test this hypothesis. We investigate whether social interactions--and especially the extent to which social network partners perceive themselves to be at risk--exert causal influences on respondents' risk perceptions and on one approach to prevention, spousal communication about the threat of AIDS to the couple and their children. The study explicitly allows for the possibility that important characteristics, such as unobserved preferences or community characteristics, determine not only the outcomes of interest but also the size and composition of networks. The most important empirical result is that social networks have significant and substantial effects on risk perceptions and the adoption of new behaviors even after we control for unobserved factors.     

On the role of families and kinship networks in pre-industrial agricultural societies: An analysis of the 1698 Slavonian census

This paper uses the 1698 Slavonian census to illuminate features of social organization and productive activity of an eastern European population under the New Feudalism of the 17th century. In particular we investigate the ability of community or kinship networks to provide substitutes for missing markets in securities and production factors. It is found that kinship networks increase the efficiency of agricultural production by facilitating the exchange of oxen. This confirms contemporary reports that draft animals were the critical constraint to the expansion of agricultural output. We also find that kinship networks fail to reduce the variability of output through mutual harvest insurance. Received: 03 November 1998/Accepted: 16 June 1999     

Learning in social networks and contraceptive choice

A puzzling observation in the diffusion of modern fertility control is the persistent diversity in contraceptive practices across communities or social strata. I propose a model of “learning in social networks” to explain this diversity with the random dynamics of word-of-mouth communication. Women are uncertain about the merits of modern contraception and estimate the different qualities of available methods based on imprecise information from network partners. Their contraceptive choices are determined by this estimate and by private knowledge about one s personal characteristics. This process of social learning leads to path-dependent adoption of fertility control within, and diversity in contraceptive practices across villages or social strata.