Volume 61, Part 1, March 2007

Authors: John Blacker, Mohamed M. Ali and Gareth Jones
Title: A response to criticism of our estimates of under-five mortality in Iraq, 1980-98

According to estimates published in this journal, the number of deaths of children under five in Iraq in the period 1991-98 resulting from the Gulf War of 1991 and the subsequent imposition of sanctions by the United Nations was between 400,000 and 500,000.

These estimates have since been held to be implausibly high by a working party set up by an Independent Inquiry Committee appointed by the United Nations Secretary-General. We believe the working party's own estimates are seriously flawed and cannot be regarded as a credible challenge to our own. To obtain their estimates, they reject as unreliable the evidence of the 1999 Iraq Maternal and Child Health Survey-despite clear evidence of its internal coherence and supporting evidence from another, independent survey.

They prefer to rely on the 1973 census and on data obtained in a format that had elsewhere been rejected as unreliable 30 years earlier.

Keywords: Iraq; UN sanctions; excess mortality; childhood deaths; Gulf War
pp. 7-13.

Authors: Kenneth A. Bollen, Jennifer L. Glanville, Guy Stecklov
Title: Socioeconomic status, permanent income, and fertility: A latent variable approach

This paper examines how permanent income and other components of SES are related to fertility in less developed countries. Because permanent income cannot be measured directly, we employ a latent-variable method.

We compare our results with those of the more common proxy-variable method and investigate the consequences of not accounting for measurement error. Using data from Ghana and Peru, we find that permanent income has a large, negative influence on fertility and that research must take the latent nature of permanent income into account to uncover its influence. Controlling for measurement error in the proxies for permanent income, can also lead to substantial changes in the estimated effects of control variables. Finally, we examine which of the common proxies for permanent income most closely capture the concept.

The results have implications beyond this specific dependent variable, providing evidence on the sensitivity of microanalyses to the treatment of long-term economic status.

Keywords: permanent income; income; wealth; socioeconomic status; fertility; measurement error; proxies; latent variable; less developed countries
pp. 15-34. 

Authors: Ronald R. Rindfuss, Martin Piotrowski, Varachai Thongthai, Pramote Prasartkul
Title: Measuring housing quality in the absence of a monetized real estate market

Measuring housing quality or value or both has been a weak component of demographic and development research in less developed countries that lack an active real estate (housing) market. We describe a new method based on a standardized subjective rating process. It is designed to be used in settings that do not have an active, monetized housing market.

The method is applied in an ongoing longitudinal study in northeast Thailand and could be straightforwardly used in many other settings. We develop a conceptual model of the process whereby households come to reside in high-quality or low-quality housing units. We use this theoretical model in conjunction with longitudinal data to show that the new method of measuring housing quality behaves as theoretically expected, thus providing evidence of face validity.

Keywords: housing quality; standardized subjective rating; building elements; household wealth; Thailand; longitudinal studies
pp. 35-52. 

Authors: Hilde Bras and Muriel Neven
Title: The effects of siblings on the migration of women in two rural areas of Belgium and The Netherlands, 1829-1940

This study explores the extent to which the presence and activities of siblings shaped the chances of women migrating to rural and urban areas in two rural areas of Belgium and The Netherlands during the second half of the nineteenth and first decades of the twentieth century.

Shared frailty Cox proportional hazard analyses of longitudinal data from historical population registers show that siblings exerted an additive impact on women's migration, independently of temporal and household characteristics. Just how siblings influenced women's migration depended on regional modes of production and on employment opportunities. In the Zeeland region, sisters channelled each other into service positions. In the Pays de Herve, where men and women found industrial work in the Walloon cities, women were as much influenced by their brothers' activities.

Evidence is found for two mechanisms explaining the effects of siblings: micro-economic notions of joint household decision-making, and social capital theory.

Keywords: siblings; migration; joint-household decision-making; social capital theory; social networks; life course; The Netherlands; Belgium; event history analysis

Author: John Bongaarts
Title: Late marriage and the HIV epidemic in sub-Saharan Africa

The causes of large variation in the sizes of HIV epidemics among countries in sub-Saharan countries are not well understood. Here we assess the potential roles of late age at marriage and a long period of premarital sexual activity as population risk factors, using ecological data from 33 sub-Saharan African countries and with individual-level data from Demographic and Health Surveys (DHS) in Kenya and Ghana in 2003.

The ecological analysis finds a significant positive correlation between HIV prevalence and median age at first marriage, and between HIV prevalence and interval between first sexual intercourse and first marriage. The individual-level analysis shows that HIV infection per year of exposure is higher before than after first marriage.

These findings support the hypothesis of a link between a high average age at marriage and a long period of premarital intercourse during which partner changes are relatively common and facilitate the spread of HIV.

Keywords: HIV; marriage; sexual behaviour; AIDS epidemic; incidence; prevalence; sub-Saharan Africa
pp. 73-83.

Authors: Siu Lan Karen Cheung and Jean-Marie Robine
Title: Increase in common longevity and the compression of mortality: The case of Japan

This study shows a strong increase in the modal age at death (M) in Japan over a period of 50 calendar years, accompanied by a clear decrease in the standard deviation of ages at death above M (SD(M+)) until the 1990s for men and the mid-1980s for women.

For the most recent periods SD(M+) appears to have stopped decreasing, even though M has continued to increase linearly. This stagnation in SD(M+) has been accompanied by stagnation in q(M). The number of deaths at M (d(M)) and the number of deaths at and above M (d(M+)) have increased, but significantly more slowly since the period 1975-79. Since the 1980s an acceleration in the increase of M+kSD(M+), our indicator of the longest life durations, has been essentially due to the pause in SD(M+). Our data do not suggest that we are approaching an upper limit in human longevity.

Keywords: modal age at death; Japan; compression of mortality; shifting mortality; longevity
pp. 85-97. 

Authors: M.A. Jonker and A.W. van der Vaart
Title: Correcting missing-data bias in historical demography

Studies on population history are often based on incomplete records of life histories. For instance, in studies using data obtained from family reconstitution, the date of death is right censored (by migration) and the censoring time is never observed. Several methods for the correction of mortality estimates are proposed in the literature, most of which first estimate the number of individuals at risk and then use standard techniques to estimate mortality.

Other methods are based on statistical models. In this paper all methods are reviewed, and their merits are compared by applying them to simulated and to seventeenth-century data from the English parish of Reigate. An ad hoc method proposed by Ruggles performs reasonably well. Methods based on statistical models, provided they are sufficiently realistic, give comparable accuracy and allow the estimation of several other quantities of interest, such as the distribution of migration times.

Keywords: parish registers; life span; missing data; estimation; bias correction; imputation methods; maximum likelihood method; right censoring; unobserved censoring time; simulation study
pp. 99-113.