Choice of purchasing arrangements in insurance markets

A simple dynamic model helps explain why risk-pooling purchasing arrangements evolved for health, disability, and term life insurance but not for property, automobile, or homeowners' insurance, and why whole-life policies typify life insurance purchased on an individual basis. We show that risk-pooling purchases facilitate insurance against unpredictable changes in one's risk type, but such contracts prevail in competitive equilibrium only when the loss probabilities increase with age, as they do for health, disability, and life insurance. In contrast, when the loss probability declines with age (as it does for automobile insurance), then competitive equilibrium entails separating insurance contracts.     

Bayesian analysis of spatial point processes in the neighbourhood of Voronoi networks

A model for an inhomogeneous Poisson process with high intensity near the edges of a Voronoi tessellation in 2D or 3D is proposed. The model is analysed in a Bayesian setting with priors on nuclei of the Voronoi tessellation and other model parameters. An MCMC algorithm is constructed to sample from the posterior, which contains information about the unobserved Voronoi tessellation and the model parameters. A major element of the MCMC algorithm is the reconstruction of the Voronoi tessellation after a proposed local change of the tessellation. A simulation study and examples of applications from biology (animal territories) and material science (alumina grain structure) are presented.     

A portrait of America's children: The impact of poverty and a call to action

The responsibility for children's services is disseminated between a multitude of advocacy organizations, social service agencies, and numerous departments within our government. A lack of conceptual integration and fiscal commitment is evident at the federal, state, and local levels. The examination of poverty and children's lack of economic security, inadequate medical care, homelessness, and nutrition inadequacies reveals a portrait of America's children that is both unsettling and alarming. The paper concludes with a call for action and the commitment that will be required to rectify this problem.     

A microcosm study of the common night crawler earthworm (<Emphasis Type="Italic">Lumbricus terrestris</Emphasis>) and physical,chemical and biological properties of a designed urban soil

Designed soils are used in specialized urban areas, such as under sidewalks or on roof-tops. These substrates have coarse light-weight aggregates to meet load-bearing specifications with soil in voids for rooting medium. A full-factorial microcosm approach was used to study Lumbricus terrrestris (two adult worms added and no-worms added), compaction (bulk density of 1.95 and 1.48 g cm⁻³), and litter (litter and no-litter additions) in a designed soil. Earthworm biomass, soil physical, chemical, and biological properties, anion leaching and surface C efflux was measured on days 0, 7, 14, 21, 28, 72, 112, and 140. Earthworms decreased bulk density in compacted soil, but did not impact density of un-compacted soil. Earthworm biomass increased days 7 to 14, but declined from days 28 to 140, likely as result of the abrasiveness of the aggregate component and relatively shallow depth of the soil (25 cm). During the period of increasing earthworm biomass, surface C efflux, microbial biomass N, soil Ca²⁺ and NH₄⁺ increased with earthworms. During the period of declining earthworm biomass, surface C efflux, microbial biomass N, soil Ca²⁺ and NO₃⁻, and leachate NO₃⁻ increased, and soil pH decreased with earthworms. While alive and dying, Lumbricus terrestris stimulated microbial activity and biomass and nutrient availability, but an apparent shift to nitrification was observed as earthworm biomass declined. The results show Lumbricus terrestris to improve designed soil properties for plants, but the improvements may be short-lived due to the inability of these earthworms to survive in the designed soil.     

Efficacy of a web-based, tailored, alcohol prevention/intervention program for college students: 3-month follow-up

This study presents the results of an efficacy evaluation of a web-based brief motivational alcohol prevention/intervention program called Michigan Prevention and Alcohol Safety for Students (M-PASS). Four on-line sessions providing individually-tailored feedback were delivered to first-year college students over 9 weeks. Non- and low-risk drinking participants received risk prevention, while high-risk drinking participants received a risk-reduction intervention. Both intervention and control groups were surveyed at baseline and at a 3-month follow-up. Analysis showed positive effects for both men and women on stage of change, drinking behavior, drinking motivation and attitudes, and use of risk-reduction strategies. These results provided evidence of efficacy and found that M-PASS had both intervention and prevention effects, making it unique among currently developed brief alcohol interventions for college students.     

Do family planning programs enhance children's health?

The findings of the 1993 National Demographic Survey (NDS) in the Philippines provide implications for child health of family size and whether a child was wanted at the time of conception. About 15% of the more than 8000 births considered in the NDS were classified as unwanted. In 1995, the East-West Center's Program on Population has helped research centers in the Philippines to conduct an extended analysis of NDS results. Children under age 5 who had been unwanted at the time of conception (unwanted children) were almost 25% and 15% more likely to have had diarrhea or respiratory infections, respectively, in the last two weeks than those who were wanted at the time of conception (wanted children). Unwantedness had little effect on the likelihood of treatment once the child was ill, however. When the researchers controlled all other variables, including unwantedness, family size did not have a direct influence on the likelihood that a child would become ill, but it did have a significant influence on whether or not an ill child would receive treatment. Each additional sibling reduced the likelihood that an ill child would receive treatment by about 5% for diarrhea and by about 4% for respiratory infection. Another factor that influenced disease incidence was age (at 18 months, most likely to be ill with respiratory infection or diarrhea). Older children were more likely to receive treatment than younger children. Other factors influencing treatment and disease incidence were socioeconomic status and maternal educational status. These findings further justify family planning programs based on child health. They demonstrate that children suffer when they are born into a household where they are not wanted. Since about 33% of all child deaths are caused by diarrhea or respiratory infections in the Philippines, unwantedness affects the incidence of these infections, and family size has a direct effect on the likelihood an ill child will receive treatment. A policy intervention that would greatly reduce child mortality would be extremely beneficial.     

Why does migration decrease fertility? Evidence from the Philippines

We model the impact of past migration on fertility, assessing the separate effects of relative urbanization of the destination, as a proxy for norms, and post-migration employment, as a proxy for opportunity costs. In the Philippines, we find that large fertility declines accompany post-migration employment. If not followed by work for pay, the estimated fertility impact of migration is small. We find little evidence of migrant selectivity in fertility, and offer speculative evidence that fertility disruption accompanying migration may be large enough to account for much of the apparent effect of normative adaptation.     

Underemployment across immigrant generations

The employment circumstances of immigrants and their children constitute a key dimension along which immigrant adaptation to the U.S. can be evaluated. We describe and analyze employment adequacy—defined as underemployment—among first, second and third (or higher) immigrant generations. Analyzing CPS data for the decade spanning 1995–2004, we find support for the notion of successful economic assimilation. The prevalence of underemployment is decidedly higher among the first-generation compared to the second or third, while the latter two groups differ little in this regard. These gross comparisons, however, mask important variation within immigrant generations, including a particular disadvantage among foreign-born non-citizens.