Distinctive features of age-specific fertility profiles in the English-speaking world: common patterns in Australia,Canada, New Zealand and the United States, 1970-98

The paper seeks to identify common features in the fertility patterns of the English-speaking world and provide a model basis for comparison of fertility between countries and over time. Attention is focused on the heterogeneity within the fertility patterns of Australia, Canada, New Zealand, and the United States, similar to that reported earlier for the UK and the Irish Republic. The recent age-specific fertility patterns of these countries display a marked 'bulge' in fertility of women under age 25. A mixture model with two-component Hadwiger functions provides a suitable fit. The heterogeneity thus suggested is related to the proportion of births outside marriage. Additionally, there is some evidence that, in the United States, and lesser extent in New Zealand, this heterogeneity in fertility patterns may be explained by ethnic difference in the timing and number of births.     

Comparability of Health Care Responsiveness in Europe

The aim of this paper is to measure and to correct for the potential incomparability of responses to the SHARE survey on health care responsiveness. A parametric approach based on the use of anchoring vignettes is applied to cross-sectional data (2006–2007) in eleven European countries. More than 7,000 respondents aged 50 years old and over were asked to assess the quality of health care responsiveness in three domains: waiting time for medical treatment, quality of the conditions in visited health facilities, and communication and involvement in decisions about the treatment. Our results suggest that there is reporting heterogeneity across countries and across individuals within countries, and the degree of heterogeneity varies with the health care domain. Although leading countries in terms of health care responsiveness remain among the most successful even after correction for reporting heterogeneity, one may acknowledge many shifts in the ranking of the other countries.     

Computer Models of Social Processes: The Case of Migration

The demographic model is a program for representing births, deaths, migration, and social mobility as social processes in a non-stationary stochastic process (Markovian). Transition probabilities for each age group are stored and then retrieved at the next appearance of that age cohort. In this way new transition probabilities can be calculated as a function of the old transition probabilities and of two successive distribution vectors.Transition probabilities can be calculated to represent effects of the whole age-by-state distribution at any given time period, too. Such effects as saturation or queuing may be represented by a market mechanism; for example, migration between metropolitan areas can be represented as depending upon job supplies and labor markets. Within metropolitan areas, migration can be represented as invasion and succession processes with tipping points (acceleration curves), and the market device has been extended to represent this phenomenon.Thus, the demographic model makes possible the representation of alternative classes of models of demographic processes. With each class of model one can deduce implied time series (varying parame-terswithin the class) and the output of the several classes can be compared to each other and to outside criteria, such as empirical time series.     

Increasing Migration,Diverging Communities: Changing Character of Migrant Streams in Rural Thailand

This paper studies how increasing migration changes the character of migrant streams in sending communities. Cumulative causation theory posits that past migration patterns determine future flows, as prior migrants provide resources, influence, or normative pressures that make individuals more likely to migrate. The theory implies exponentially increasing migration flows that are decreasingly selective. Recent research identifies heterogeneity in the cumulative patterns and selectivity of migration in communities. We propose that this heterogeneity may be explained by individuals’ differential access to previously accumulated migration experience. Multi-level, longitudinal data from 22 rural Thai communities allow us to measure the distribution of past experience as a proxy for its accessibility to community members. We find that migration becomes a less-selective process as migration experience accumulates, and migrants become increasingly diverse in socio-demographic characteristics. Yet, selectivity within migrant streams persists if migration experience is not uniformly distributed among, and hence not equally accessible to, all community members. The results confirm that the accumulation and distribution of prior migrants’ experiences distinctly shape future migration flows, and may lead to diverging cumulative patterns in communities over time.     

The consequences of unobserved heterogeneity in a sequential logit model

Cameron and Heckman (1998) established that a sequential logit model is more sensitive than many other models to the possible biasing influence of unobserved heterogeneity. This article proposes a method which allows researchers to find out how large this potential problem is for their data, their model, and their hypothesis of interest. This is done by proposing a set of scenarios for this unobserved heterogeneity, and showing how to estimate the effects of interest given these scenarios. The set of results from these scenarios give an indication of how sensitive the results are to assumptions regarding unobserved heterogeneity. This sensitivity analysis has been applied to a study of educational attainment in the Netherlands, and it showed that that the finding that the effect of father's education declined over transitions is quite sensitive to the assumptions made about unobserved heterogeneity, but that the finding that the effect of father's education declined over birth cohorts is more robust than is often feared.     

Heterogeneity and selection in multistate population analysis

If one subgroup of individuals in a population has a higher death rate than the others, then over time the surviving population will include a larger share of those with the lower death rate. As a result, the aggregate average death rate for this increasingly more robust population will decline. This conclusion, however, can be drawn only for nonrecurrent events experienced by populations that do not exchange members with one another--that is, for noninteracting populations. Studies of changes in marital status, labor force activity, residential location, and active life, for example, all should focus on patterns of recurrent events among interacting populations (that is, multistate populations). Selection arising from heterogeneity will occur, but the consequences for average measures become unpredictable a priori. This paper explores such aspects of the selection effects of heterogeneity in multistate populations and illuminates some of their consequences for commonly used rates.     

Mortality Deceleration and Mortality Selection: Three Unexpected Implications of a Simple Model

Unobserved heterogeneity in mortality risk is pervasive and consequential. Mortality deceleration—the slowing of mortality’s rise with age—has been considered an important window into heterogeneity that otherwise might be impossible to explore. In this article, I argue that deceleration patterns may reveal surprisingly little about the heterogeneity that putatively produces them. I show that even in a very simple model—one that is composed of just two subpopulations with Gompertz mortality—(1) aggregate mortality can decelerate even while a majority of the cohort is frail; (2) multiple decelerations are possible; and (3) mortality selection can produce acceleration as well as deceleration. Simulations show that these patterns are plausible in model cohorts that in the aggregate resemble cohorts in the Human Mortality Database. I argue that these results challenge some conventional heuristics for understanding the relationship between selection and deceleration; undermine certain inferences from deceleration timing to patterns of social inequality; and imply that standard parametric models, assumed to plateau at most once, may sometimes badly misestimate deceleration timing—even by decades.     

Family Size,Cognitive Outcomes,and Familial Interaction in Stable,Two-Parent Families: United States, 1997–2002

Measures of children’s time use, particularly with parents and siblings, are used to evaluate three hypotheses in relation to the vocabulary and mathematical skills development: (1) the resource dilution hypothesis, which argues that parental and household resources are diluted in larger families; (2) the confluence hypothesis, which suggests that the intellectual milieu of families is lowered with additional children; and (3) the admixture (“no effect”) hypothesis, which suggests that the negative relationship between family size and achievement is an artifact of cross-sectional research resulting from unobserved heterogeneity. Each hypothesis is tested using within-child estimates of change in cognitive scores over time with the addition of new children to families.     

Modeling urbanism: Economic,social and environmental stress in cities

The time has come for urban social indicator research to converge with the basic substantive efforts of urban researchers. Such a convergence may propel both basic and applied researchers toward more fruitful outcomes. This paper argues that the traditional model of urbanism provides the medium for the convergence. When urbanism is conceptualized to be multidimensional, seemingly discreet indicators of demographic, economic, social, and environmental conditions in cities may be incorporated into a more general model of urban structure and change. Specifically, using social indicators for 195 cities from ZPG's Children's Stress Index and the 1990 U.S. Census, we show empirically: (1) Urbanism is a complex factor with four distinct dimensions: demographic scale, economic stress, social stress, and environmental stress. (2) These four dimensions of urbanism may be reliably measured with standard composite variables used in today's social indicator research. (3) Within the Urbanism factor there are causal connections among the separate dimensions, the most basic of which is that asserted by arguments from the traditional theory of urbanism; specifically, that population size, density, and social heterogeneity are causally linked to stress in economic, social, and environmental systems of the city.     

When Does Time Matter? Maternal Employment,Children’s Time With Parents,and Child Development

This study tests the two assumptions underlying popularly held notions that maternal employment negatively affects children because it reduces time spent with parents: (1) that maternal employment reduces children’s time with parents, and (2) that time with parents affects child outcomes. We analyze children’s time-diary data from the Child Development Supplement of the Panel Study of Income Dynamics and use child fixed-effects and IV estimations to account for unobserved heterogeneity. We find that working mothers trade quantity of time for better “quality” of time. On average, maternal work has no effect on time in activities that positively influence children’s development, but it reduces time in types of activities that may be detrimental to children’s development. Stratification by mothers’ education reveals that although all children, regardless of mother’s education, benefit from spending educational and structured time with their mothers, mothers who are high school graduates have the greatest difficulty balancing work and childcare. We find some evidence that fathers compensate for maternal employment by increasing types of activities that can foster child development as well as types of activities that may be detrimental. Overall, we find that the effects of maternal employment are ambiguous because (1) employment does not necessarily reduce children’s time with parents, and (2) not all types of parental time benefit child development.     

Psychosocial environments of black colleges: A theory-based assessment

Holland's theory of person environment interactions has considerable potential for helping to integrate environmental psychology with personality social psychology. This study applied measures based on his theory to the environments of black colleges. Compared to the U.S. labor force as a whole, blacks are over represented in social service careers and under represented in technical and managerial careers, and it is possible that the environments provided by black colleges may help cause or perpetuate this distribution of blacks among careers. Accordingly, the faculties of predominantly black colleges and of a representative sample of U.S. postsecondary institutions were classified in terms of Holland's six types: Realistic, Investigative, Artistic, Social, Enterprising, and Conventional. Compared to U.S. colleges as a whole, the faculties of black colleges are relatively more concentrated in Social fields and relatively less concentrated in Realistic and Enterprising fields. Thus the environments of black colleges and universities resemble the distribution of blacks among careers. These results imply that efforts to improve black colleges might emphasize recruitment of faculty members in Realistic and Enterprising fields. Implifications for environmental psychologists working in other contexts are considered.Recently, a number of writers have pointed to a growing rapprochement between environmental psychology and the field of personality social psychology (Canter & Craik, 1981; Little 1983). This trend suggests that Holland's (1966a, 1985) theory of person environment interactions may have considerable utility for environmental psychology. This theory has received little attention from environmental psychologists, perhaps because it grows out of counseling and educational psychology and therefore is outside the experience of many environmental psychologists (Richards, 1974a). It offers major advantages, however, in that it explicitly views personality and environments in terms of a common conceptual framework, and that it predicts the consequences of personality environment interactions.One of the major applications of this theory has involved the assessment of the environments provided by institutions of higher education. More specifically, the theory has been applied successfully to two-year and four-year colleges and universities in the United States (Astin, 1963; Astin & Holland, 1961; Richards, Bulkeley, & Richards, 1972; Richards, Seligman, & Jones, 1970), to Japanese universities (Richards, 1973, 1975), and to universities in the British Commonwealth (Richards, 1974b, 1975). The present study used measures derived from the theory to compare the environments of black colleges and universities with the environments of U.S. colleges and universities in general.This comparison was deemed important because of the possibility that black colleges may be playing a role in causing or perpetuating an occupational distribution in which blacks are over represented in low status social service occupations (Hodge & Hodge, 1965; Treiman & Terrell, 1975) and under represented in technical and managerial occupations (Gottfredson, 1978a, 1978b). Colleges that are traditionally black have produced the majority of past black college college graduates and still appear to be the most important means of access to afour-year college education for blacks (National Advisory Committee on Black Higher Education and Black Colleges and Universities, 1979). At the same time, the distribution of students among majors in traditionally black institutions is generally consistent with the relative representation of blacks in different types of work (Morris, 1979).     

Is Economic Policy Uncertainty Related to Suicide Rates? Evidence from the United States

The main objective of this paper was to see whether different countries around the world show differences in their sustainability levels as captured in the indicators from the Sustainable Society Index (SSI, Van de Kerk and Manuel in Ecol Econ 66:228–242, 2012) according to their level of income. To do so, the X-STATIS and CO-STATIS multivariate techniques were employed. With these methods, our sample of 151 countries and 21 indicators can be jointly represented along four time periods. The results obtained permit us to visualize that the groups of countries by income levels show differences in some of the variables from the SSI, because of the lack of proximities between those variables and the countries. Moreover, with the X-STATIS technique, the possible evolution of the countries or indicators over time can be represented, and with CO-STATIS, the relations between the social, economic and environmental aspects can be shown as well. From our results we were able to deduce that, on the one hand, social and economic indicators, such as Public Debt or Employment, are associated with countries having high and upper-middle incomes, for example, Chile, Israel, Malta, Kuwait, Saudi Arabia, Oman, Spain, Portugal, France, Poland and Czech Republic. On the other hand, countries with low and lower-middle incomes are more associated with environmental issues. Also, after finding that the differences between the countries by income levels are mainly caused by the economic indicators, we carried out two CO-STATIS analyses, one for social and economic variables, and the other for economic and environmental variables. These findings led us to deduce that, generally, the social and economic indicators are not related to each other, nor are the economic indicators related to the environmental ones. However, for some of the countries individually both relations may be possible.     

Simulation of movement and egglaying inDanaus plexippus (Lepidoptera: Nymphalidae)

Summary A model simulating the movement and oviposition of monarch butterflies over a female's life time is presented. The model's predictions compare favourably with observed data and suggest that females who lay eggs in an optimal fashion should have low directionalities in areas with high host plant density (patches and single plants) and high directionalities in areas with low host plant density. The model also provides one means of combining individual animal processes and spatial heterogeneity into population dynamics.     

Decomposing change in life expectancy: A bouquet of formulas in honor of Nathan Keyfitz’s 90th birthday

We extend Nathan Keyfitz's research on continuous change in life expectancy over time by presenting and proving a new formula for decomposing such change. The formula separates change in life expectancy over time into two terms. The first term captures the general effect of reduction in death rates at all ages, and the second term captures the effect of heterogeneity in the pace of improvement in mortality at different ages. We extend the formula to decompose change in life expectancy into age-specific and cause-specific components, and apply the methods to analyze changes in life expectancy in Sweden and Japan.     

Estimation of Exposure Time Distributions

In many demographic analyses, such as the assessment of environmental cancer risks, one may be interested not only in the age-by-state distribution of the population but also in the distribution of the population by time spent in a given state. States can represent geographic areas, marital statuses, labor force participation, or states of epidemiologic exposure. Recursive formulas for the calculation of the distribution of the population according to exposure time are derived under time-invariant state transition rates. Although populations can have identical growth rates and identical age-by-state distributions, they can have very different distributions by exposure time. An application to the analysis of carcinogenic exposure states is given, using data from Finland. The effect of population heterogeneity on the estimated exposure time distributions is studied.     

A mathematical model of the food-consumer system I. A case without food replenishment

Summary A simple mathematical model was proposed to describe the dynamics of a food-consumer system. The model was based on the Logistic Theory and consisted of Eqs. (4), (5) and (6). The model was divided into the following three cases for further analyss; i) without food supply except at the initial time, ii) with continuous food supply at a constant rate, and iii) with food supply at varying rates. Only the first model was dealth with in this paper. The assumptions of the model 1 are that a definite amount of food is given only once at the initial time and only the feeding by animals is responsible for the decrease of food, and that the rate of decrease is proportional to the amount of animals. It is also assumed that the growth of animal population is represented by the logistic curve, and that the upper limit of the population is proportional to the amount of food at that time. For simplicity the parameters of basic differential equations are assumed to be constant throughout the time course. Analytical solutions of this non-linear model were given by Eqs. (8), (9), (10) and (11). The properties of time course of the food amount and consumer population were discussed from the mathematical and biological points of view. The method of the estimation of the three constants λ,b, andc from the experimental data was also suggested. Since we had no available data for animal populations, we applied the model, regarding reserve substance asx and new plant body asy, to the data of the initial growth of Azuki bean plant in the dark. This model is very simple, but it may be useful for analyzing the behavior of food-consumer system. And it may give some clue to the analysis of the more complex systems.     

Heterogeneity in the Strehler-Mildvan General Theory of Mortality and Aging

This study examines and further develops the classic Strehler-Mildvan (SM) general theory of mortality and aging. Three predictions from the SM theory are tested by examining the age dependence of mortality patterns for 42 countries (including developed and developing countries) over the period 1955–2003. By applying finite mixture regression models, principal component analysis, and random-effects panel regression models, we find that (1) the negative correlation between the initial adulthood mortality rate and the rate of increase in mortality with age derived in the SM theory exists but is not constant; (2) within the SM framework, the implied age of expected zero vitality (expected maximum survival age) also is variable over time; (3) longevity trajectories are not homogeneous among the countries; (4) Central American and Southeast Asian countries have higher expected age of zero vitality than other countries in spite of relatively disadvantageous national ecological systems; (5) within the group of Central American and Southeast Asian countries, a more disadvantageous national ecological system is associated with a higher expected age of zero vitality; and (6) larger agricultural and food productivities, higher labor participation rates, higher percentages of population living in urban areas, and larger GDP per capita and GDP per unit of energy use are important beneficial national ecological system factors that can promote survival. These findings indicate that the SM theory needs to be generalized to incorporate heterogeneity among human populations.     

Trend Analysis of Medical Publications About LGBT Persons: 1950–2007

Although there are currently at least 6 million lesbian, gay, bisexual, and transgender (LGBT) persons in the United States, there are no prior studies analyzing how this group is represented in the medical literature. An examination of published LGBT topics over a 57-year period was performed using OvidSP. A total of 21,728 publications was analyzed for topic using information from the title, keywords, subject headings, and abstracts. Several trends became apparent. The largest proportion of LGBT publications (31.78%) was devoted to HIV/AIDS and other sexually transmitted infections (STIs), yet there was an overall lack of emphasis on general health topics or common causes of mortality. Further analysis showed that if publications on HIV/AIDS or STIs addressed sexual orientation, they were more likely to be about LGBT persons than heterosexuals. Overall, the volume and range of medical publications on LGBT persons may not be reflective of the health care needs of this population.