The population dynamics of the voleClethrionomys rufocanus in Hokkaido, Japan

Population dynamics of the gray sided-vole,Clethrionomys rufocanus, in Hokkaido, Japan were described on the basis of 225 time series (being from 12 to 31 years long); 194 of the time series have a length of 23 years or longer. The time series were classified into 11 groups according to geographic proximity and topographic characteristics of the island of Hokkaido. Mean abundance varied among populations from 1.07 to 21.07 individuals per 150 trap-nights. The index of variability for population fluctuation (s-index) ranged from 0.204 to 0.629. Another index for population variability (amplitude on log-10 scale) ranged from 0.811 to 2.743. Mean abundance and variability of populations were higher in the more northern and eastern regions of the island. Most populations, except for the southernmost populations, exhibited significant direct density-dependence in population growth. Detection rate for delayed density-dependence varied among groups from 0% to 22.6%. Both direct and delayed density-dependence tended to be stronger in the more northern and eastern populations. The proportion of cyclic populations was higher in the northern-eastern areas than that in the southern-western areas. There was a clear gradient from the asynchronous populations in southwest, to the highly synchronized populations in the northeast.     

Age structure,growth, attrition and accession: A new synthesis

This paper shows that each equation describing relationships among demographic parameters in a stable population is a special case of a similar and equally simple equation that applies to any closed population and demonstrates some implications of these new equations for demographic theory and practice. Much of formal demography deals with functions that pertain to individuals passing through life, or to a stationary population in which births of individuals are evenly distributed over time. These functions include life expectancy, probabilities of survival, net and gross reproduction rates, expected years spent in various states and the probability that certain events will occur in the course of life. The stable population model permits the translation of population structure or processes in a more general type of population, with constant growth rates, back into equivalent populations for a stationary population. The method for translation developed in this paper, requiring only a set of age-specific growth rates is even more general, applying to any population. Age specific growth rates may also be useful for performing reverse translations, between a population's life table and its birth rate or its age distribution. Tables of numbers of females by single years of age in Sweden are used to illustrate applications. Tables summarize the basic relations among certain functions in a stationary population, a stable population and any population. Applications of new equations, particularly to demographic estimation of mortality, fertility and migration, from incomplete data, are described. Some other applications include; the 2 sex problem, increment decrement tables, convergence of population to its stable form, and cyclical changes in vital rates. Stable population models will continue to demonstrate long term implications of changes in mortality and fertility. However, in demographic estimation and measurement, new procedures will support most of those based on stable assumptions.     

A model of the species rank-abundance relation for a community in an open habitat

Summary A mathematical model is proposed to describe the relationship between the abundance and the rank of species in order from the most abundant to the least in a community in an open habitat. This model is derived as a corollary of a species-area equation (Kobayashi, 1975) which could be expected in the case where the individuals of each species are uniformly distributed over a habitat area. Numerical simulation reveals that a rank-abundance curve for a universe results in different species-area or species-individual curves according to the spatial distribution of individuals, and that the relative abundance of each species in a sample varies with sample size unless the spatial distribution of individuals is uniform. A species-individual curve obtained bySanders’s (1968) rarefaction method agrees with that observed actually only for the spatially uniform distribution. Change in the pattern of rank-abundance curve with species diversity and with sample size is discussed in relation to the present model.     

Statistical analysis of occupancy rates for overdispersed populations by redistribution procedures: Application to the european corn borer EGG masses distribution

Summary Standard statistical analyses of distributions of individuals from contingency tables are generally invalid if the individuals are not distributed independently of each other. In this paper, we discuss a method of testing hypotheses about classification category occupancy rates for overdispersed population or for population whose individuals are distributed by groups rather than lonely. These methods are based on population redistribution simulations and provide valid, exact and powerful tests in situations for which classical methods are not appropriate. Illustrations are given from the European Corn Borer eggs data.     

Food limitation of population density in the orb-wed spider,Nephila clavata

Summary Field studies were conducted to clarify whether variation in food availability among habitats influences population density, and whether population density has a negative effect on foraging success in the orb-web spider,Nephila clavata. Lifetime food consumption per individual (i.e., foraging success) strongly correlated with mean body size of adult females and mean fecundity in populations. Also, there was a positive correlation between foraging success and population density. Since foraging success reflected potential prey availability in the habitat, food resource appeared to be a limiting factor for populations in this spider. Mean fecundity per individual correlated with population density of the following year, suggesting that decreased reproduction is a major component of food limitation on population density. Consistent defferences in mean body size between particular sites were observed over years, while such difference was less obvious in density. Thus, ranking of food abundance among habitats seems to be predictable between years. A field experiment revealed that an artificial increase in population density had no negative effect on the feeding rate of individuals, suggesting that intraspecific competition for food is not important in this species.     

Urban segregation in Sweden housing policy,housing markets,and the spacial distribution of households in metropolitan areas

The postwar Swedish housing standard has been raised considerably. But there were also unforeseen and undesired side effects in the form of increasing segregation. Between 1965–1975 a great number of rental apartments were built in the periphery of the metropolitan areas. They originally received an overrepresentation of the poor, immigrants, social welfare recipients, and members of the working class. Today these areas face long distances, increasing deterioration and the lower socioeconomic level of their population is accentuated. The following wave of rebuilding in the central metropolitan areas also reinforced residential segregation. As the dwellings became larger and totally modern, the rents rose. Ownership forms often changed to tenant-owned dwellings which drove up the prices of tenant-owned dwellings. The older working-class population was replaced by wealthy families with middle-class backgrounds. The rebuilding in the city centers has in all likelihood been the motor in the overall relocations and migrations of the metropolitan populations during the 1980s. The movement of the middle-class towards the centers corresponds to an increased concentration of workers and various resource-weak groups on the peripheries. This analysis uses a new large micro data base integrating Swedish census and level-of-living survey data on individuals, households and neighbourhoods.Housing segregation has not been seen as a very serious problem in Sweden. Attention has primarily been aimed at providing spatial and modern dwellings for everyone. The construction of housing was explosive through the middle of the 1970s, and it has been supported by substantial general subsidies. Today, Sweden, together with Norway, has Europe's highest and most evenly distributed housing standard. Overcrowding and unmodern housing have for all practical purposes been abolished.     

Homosexual Discretion and Good Taste: Two Rules That Govern Homosexual Sociability Space in Santiago de Chile

Homosexual sociability space in Santiago is not socially homogenous. Beyond non-heterosexual identities segmentation (gay, lesbian, queer, BDSM, etc.), the present article proposes a reflection observing certain social distinctions or differences that come into play to create a hierarchy among gay and lesbian individuals within that space. Using a qualitative approximation, we analyze the discourse of homosexual men and women about ways to display homosexuality in different places in the city, as well as some sociability practices used in homosexual venues. The resulting social hierarchy is understood through two central subjective rules: discretion and good taste, dynamic mechanisms that perpetuate the distance among groups within the same sociability space, and to some extent reproduce the city’s class structure. Given that material means to privatize and sophisticate homosexual expression are unequally distributed in Santiago, the resulting differentiated social networks end up configuring the visibility strategies of homosexual identity played out in the city in the last years.     

Bridging 1990 and 2000 census race data: Fractional assignment of multiracial populations

In contrast to previous censuses, Census 2000 permitted individuals to mark more than one race. Because the new race tables include both single-race and mixed-race categories, measuring change during the 1990s requires some method of bridging between the two data sets.To accomplish this bridging, we first identified biracial populations as of 1990 through the race and ancestry responses of individuals in the PUMS file. With race responses assumed to represent a person's primary race identity, we then determined the percentage of each biracial group that preferred each race as the primary identity. The same percentages can be used to assign biracial persons from Census 2000 into single-race categories. We also provide fractional assignment percentages for selected states and for the larger specific nationality groups of mixed-race Asians.Comparison of our 1990 estimates of the numbers in leading biracial groups with those reported in Census 2000 suggests that our fractional assignment values are reasonable for biracial groups other than those involving American Indians and Alaska Natives. For the latter biracial groups and for all groups representing three or more races, we recommend equal fractional assignment into the appropriate single-race categories.     

Comparisons among heterosexual, bisexual, and homosexual male sadomasochists

Between 1982 and 1984 a questionnaire designed to elicit demographic and behavioral information concerning individuals who participate in sadomasochism (S&M) was distributed nationally. Data from 136 heterosexual, 45 bisexual, and 91 homosexual male sadomasochists (N = 272) were analyzed. Similarities and differences among these three groups in response to 15 of the 40 questions asked concerning age and manner of first S&M interest, openness with others concerning those interests, self image and adjustment, sexual behavior, and sex role orientation are reported and compared to findings previously reported by Spengler (1977), Lee (1979), Kamel (1980), Weinberg & Falk (1980) and Weinberg, Williams, & Moser (1984). Issues concerning the categorization of the respondents into appropriate S&M sex role types are also discussed.     

Socio-economic determinants of mortality in Latin America

The characteristics and sources of socioeconomic differentials of mortality in Latin America, in so far as they are currently known, are examined in an attempt to clarify the present situation and its perspectives. Mortality in a population is a function of the frequency of illness (incidence) and the probability of dying of the sick individual (lethality). Information on the socioeconomic differentials of mortality in Latin America is systematically reviewed with attention directed to the following: differentials among Latin American countries, regional differences within countries, urban-rural contrasts in mortality, mortality and income level and level of education, and mortality and ethnic groups. Latin America shows considerable heterogeneity with respect to the risk of dying, which varies from 202/1000 births in Bolivia to 38/1000 in Uruguay. It is estimated that more than 1/2 of the children born in Latin America are exposed to a mortality rate of over 120/1000. A study of the urban and rural populations of 12 Latin American countries revealed that the risk for rural populations exceeds that for urban populations by 30-60%. There is extensive evidence showing that mortality is higher in the working class and is associated with lower levels of education and income. Mortality was also higher in certain indigenous groups. Socioeconomic differentials of mortality are more marked in Latin America than in the developed nations. The mother's level of educational attainment is the variable most significantly associated with infant and child mortality. The prospect of reducing the current mortality levels is dependent primarily upon the implementation of policies aimed at a more egalitarian distribution of the benefits of socioeconomic development among the population.     

The estimation of Unwanted Fertility

The estimation of unwanted fertility is a major objective of demographic surveys, including DHS surveys conducted in Asia, Africa, and Latin America. Levels and trends in unwanted fertility are important input to the formulation of population policy and the evaluation of family planning programs. Yet existing methods for estimating unwanted fertility are known to be defective, among other reasons because they rely on subjective data whose validity and reliability are questionable. In this article, we propose a new estimator of unwanted fertility-the "aggregate prospective estimator"--so named because it depends on the stated preference for another child at the time of the survey, the fertility-desires item consistently shown to possess the highest validity and reliability. Under reasonable assumptions, the aggregate prospective estimator produces less biased estimates of unwanted fertility than the most widely used existing methods. The new estimator has the limitation of generating only aggregate-level estimates, but such estimates are the primary data for policy formulation and program evaluation. The new estimator is presented in this article, along with an evaluation of its underlying assumptions and its sensitivity to several sources of error. In an illustrative application to recent DHS data from six countries, the new estimator yields substantially higher estimates of unwanted fertility than existing methods in all six countries.     

Validity of centenarian data in the 1960 Census

This paper examines the question of how many genuine centenarians there actually are in the United States as compared with those reported in the census. It is concluded that the numbers of centenarians shown in various United States censuses are definite overstatements of the number of true centenarians. It seems likely that instead of the 10,326 centenarians reported in the 1960 census there were at most only about 3,700. Overstatement of ages seems to be particularly the case among those who claim to be aged 110 or over, and it is believed that there probably are no persons who are actually this old.The analysis has been made by projecting, through the me of population life table survival factors, the populations reported cit carious advanced age groups in one census to the next census and then comparing the results with the corresponding number reported in the latter census for the same age cohort. In general, the enumerated populations at ages below 95 are reasonably close to the projected populations, especially for white persons. On the other hand, at ages 95 and over-especially for centenarians-the enumerated populations significantly exceed the projected ones.As a subsidiary part of the analysis, the paper points out the significant differences at the older ages between the "full count" age distribution in the 1960 census and the corresponding "inflated 25 per cent sample" one. This is a subject that bears further investigation and explanation.The paper also discusses centenarians on the social security benefit rolls and concludes that the present data cannot be considered of substantial accuracy with regard to genuine centenarians, particularly the oldest ones. In a number of years, however, this program will provide excellent data, became the individuals involved will have been on the benefit rolls for many years and will have had their ages proved with reasonable accuracy.     

Changing living arrangements: A hazard model of transitions among household types

This paper analyzes movements among household types. Persons in one household may join another type. Correspondingly, a household’s structure may change when someone joins it. Data are from the Panel Survey of Income Dynamics, spanning 1968–1980. The individuals followed in the survey generated spells analyzed with a multivariate competing risk hazard model. We develop a map of the flow among household types and of the economic and demographic profiles of individuals making the transitions. We find wide variability in the stability of household types and marked racial differences in the relative stability and pattern of destination choices.     

The fertility of two-generation urbanites

In this paper it is argued that in studies of urban fertility, the relationship between socio-economic variables and fertility has been obscured by the presence of rural migrants in the populations under investigation. Accordingly, data obtained from families of completed fertility in six probability samples of metropolitan Detroit are divided into two groups, farm migrants and two-generation urbanites.

In general, the socio-economic differences in fertility observed among the “pure” urban types in Detroit are found to be small and inconsistent, most of them being statistically insignificant. The inverse fertility pattern found in the total Detroit population is attributed to : (a) the overrepresentation of farm migrants (who have high fertility) in the lowest social and economic positions in the city, and (b) the pronounced inverse pattern of fertility among the farm migrants.

It is suggested that the absence of an inverse fertility pattern among twogeneration urbanites and its presence among the farm migrants can be attributed to differences in family organization.     

Implications of genetic variation within and between human populations

Human variation is extensive both within and between populations. This variation affects all traits, including the susceptibility to disease and responses to the environment. For social and political reasons, we tend to think of our species or our own national population as being divided into meaningful groups variously called by such terms as races, or ethnic groups, and there is often an implicit assumption that these groups are relatively homogeneous within and very different between. Examples are given to show that there are major differences in the frequency of genetic susceptibility to various diseases between some such groups, but that the amount of variation among individuals is extensive even within such groups. Population subdivision can be useful for studying disease, but human variation is a general phenomenon tied to groups via their population and geographic history, not value-based categorical differences.     

Frustrated fertility: a population paradox

This Bulletin examines the causes of subfecundity -- the diminished ability to reproduce -- and its effect today and in the past on the fertility, or actual reproductive performance, of individuals and, hence, populations. By definition, all real populations are subfecund since all experience some degree of involuntary biological factors affecting coitus, conception, or the ability to carry a conceptus to live birth which reduces their fecundity below the estimated biological population maximum of 15 children per woman. Affecting both men and women, these factors fall into 5 categories: genetic factors such as blood group incompatibilities and inherited sickle cell anemia or diabetes; psychopathology, including psychic stress and behavioral disorders (e.g., drug and alcohol abuse); infectious diseases such as gonorrhea, malaria, tuberculosis, and postabortion infection; malnutrrition, including the chronic undernutrition of the 3rd World and the overnutrition of developed societies; and hazards posed by increasing amounts of radiation and toxic chemicals in the environment. Reducing subfecundity requires improved living conditions, avoidance of or protection from known hazards, and adoption of medical advances which now can help 40 to 60% of subfecund couples. But even in the U.S. fertility would certainly rise among the 15% of couples now estimated to be involuntarily childless and the 10% who have fewer children than they want, and among disadvantaged groups, and teenagers.     

The Changing Context of Fatherhood in Canada: A life Course Analysis

Arabs in Israel are a heterogeneous but largely underprivileged minority with a history of disadvantage in several domains, including education and employment. In this paper, we document changes in their attainment of various educational levels across cohorts born from the mid-1920s to the 1970s. We make comparisons among different Arab religious groups, between men and women, and between Arabs and the majority Jewish populations in Israel. We find that over consecutive birth cohorts, substantial ethnic differences in educational attainment have narrowed at the lower levels of schooling, but have increased at higher levels. Moreover, the results indicate that the disadvantage of Muslim Arabs in terms of entry into and completion of high school can be accounted for only partially by differences in the social status of their parents and characteristics of their neighbourhoods. The findings suggest that long-term historical differences among groups and discriminatory practices towards Arabs are important factors in explanations of disparities in educational attainment.     

Educational stratification among Arabs and Jews in Israel: historical disadvantage, discrimination, and opportunity

Arabs in Israel are a heterogeneous but largely underprivileged minority with a history of disadvantage in several domains, including education and employment. In this paper, we document changes in their attainment of various educational levels across cohorts born from the mid-1920s to the 1970s. We make comparisons among different Arab religious groups, between men and women, and between Arabs and the majority Jewish populations in Israel. We find that over consecutive birth cohorts, substantial ethnic differences in educational attainment have narrowed at the lower levels of schooling, but have increased at higher levels. Moreover, the results indicate that the disadvantage of Muslim Arabs in terms of entry into and completion of high school can be accounted for only partially by differences in the social status of their parents and characteristics of their neighbourhoods. The findings suggest that long-term historical differences among groups and discriminatory practices towards Arabs are important factors in explanations of disparities in educational attainment.     

Patterns of Mental Health Care Utilization Among Sexual Orientation Minority Groups

Prior studies of the utilization of mental health professionals by sexual minority populations have relied on data that are now dated or not nationally representative. These studies have also provided mixed findings regarding gender differences in the utilization of mental health professionals among sexual minority individuals. Using data from the 2013–2015 National Health Interview Surveys, this study investigates (1) how sexual minority individuals compare to heterosexual participants in their utilization of mental health professionals; and (2) gender differences in that utilization. The results indicate sexual minority individuals utilize mental health care professionals at higher rates than heterosexual individuals even after controlling for measures of mental health and other demographic characteristics; this is true for both men and women. However, gender moderates the sexual minority effect on utilization rates. Sexual minority men utilize mental health professionals at a high rate, such that their utilization rates are similar to sexual minority women, contrary to the gender gap seen among heterosexuals.     

Decomposition of the Shrinking Middle-class and Directional Mobility in Finland 1995–2012

This paper investigates the middle-class decline in Finland from 1995 to 2012. The purpose is to examine how changes in the probabilities of belonging to the middle class in different socioeconomic groups have contributed to the middle-class decline while taking into account changes in the relative sizes of the groups. A decomposition analysis indicates that most of the decline has been due to the probability effect, especially among the least-educated population. Changes in age demographics and educational structure have contributed to the decline. The results of the decomposition are supported by mobility results, which indicate that individuals with a tertiary (no secondary) degree have been subject to upward (downward) mobility over the observed time period. In conclusion, the middle-class decline and polarization in Finland are asymmetrically reflected in different education groups. The highly educated have climbed up the income distribution, while the least educated have fallen.