Experiments in modelling recent Danish fertility curves

This paper reports the outcome of an exercise in curve fitting to annual sets of Danish age-specific fertility rates for the years 1962 to 1971 by means of least squares. Functions fitted were a cubic spline, the Hadwiger and Coale-Trussell functions, the gamma and beta densities, two versions of a polynomial, and two of Brass's relational procedures, as well as the Gompertz curve. The spline function fitted all curves far better than any of the others. The Coale-Trussell procedure and gamma density were about equal, followed by the Hadwiger function. All of these functions fit the data well. One of the polynomials fit reasonably well, but the rest of the functions were less accurate.     

Estimating detailed distributions from grouped sociodemographic data: ‘get me started in’ curve fitting using nonlinear models

In much demographic analysis, it is important to know how occurrence-exposure rates or transition probabilities vary continuously by age or by time. Often we have coarse or fluctuating data so there can be a need for estimation and smoothing. Since the distributions of rates or counts across age or another variable are often curved, a nonlinear model is likely to be appropriate. The main focus of this paper is on the estimation of detailed information from grouped data such as age and income bands; however, the methods we outline could also be applied to other settings such as smoothing rates where the original data are ragged. The ability to carry out curve fitting is a very useful skill for population geographers and demographers. Curve fitting is not well covered in statistics textbooks, and whilst there is a large literature in journals thoroughly discussing the detail of functions which define curves, these texts are likely to be inaccessible to researchers who are not specialists in mathematics. We aim here to make nonlinear modelling as accessible as possible. We demonstrate how to carry out nonlinear regression using SPSS, giving stepped-through hypothetical and research examples. We note other software in which nonlinear regression can be carried out, and outline alternative methods of curve fitting.     

Recovering event histories by cubic spline interpolation

If event data are recorded in discrete intervals of time, errors are introduced when the data are converted from the unit in which they were recorded, such as date, to another unit such as age or duration. The problem is illustrated by the inconsistent age at marriage schedules published by 2 recent US censuses. This paper develops a general method for treating problems of this type using cubic spline interpolation. The method is used to adjust US age at marriage schedules, explaining a substantial part of the discrepancy in the 1960 and 1970 censuses.     

Recovering event histories by cubic spline interpolation

If event history data are recorded in discrete intervals of time, errors are introduced when the data are converted from the unit in which they were recorded, such as date, to another unit such as age or duration. The problem is illustrated by the inconsistent age at marriage schedules published by two recent U.S. censuses. This paper develops a general method for treating problems of this type using cubic spline interpolation. The method is used to adjust U.S. age at marriage schedules, explaining a substantial part of the discrepancy in the 1960 and 1970 censuses.     

Comparison of Four Methods for Estimating Complete Life Tables from Abridged Life Tables Using Mortality Data Supplied to EUROCARE-3

ABSTRACT

To estimate mortality due to cancer, it is necessary to have mortality data by year of age in the population of cancer patients. When such data are not available, estimating one-year (complete) life tables from five-year (abridged) life tables is necessary. Four such methods—Elandt–Johnson, Kostaki, Brass logit, and Akima spline methods—are compared with respect to 782 empirical complete life tables pertaining to 19 European regions or countries, from 1954 to 2000. Abridged life tables are first derived from the empirical ones, then used to produce one-year-life tables by each of the four methods. These reconstituted complete life tables are then compared with the empirical complete life tables. Among the four methods, the Elandt–Johnson demographic method produces the best reconstitutions at adult ages, specifically those ages at which observed cancer survival needs to be corrected.     

An Empirical Analysis of the Effect of Length of Forecast Horizon on Population Forecast Errors

Many studies have found that population forecast errors generally increase with the length of the forecast horizon, but none have examined this relationship in detail. Do errors grow linearly, exponentially, or in some other manner as the forecast horizon becomes longer? Does the error-horizon relationship differ by forecasting technique, launch year, size of place, or rate of growth? Do alternative measures of error make a difference? In this article we address these questions using two simple forecasting techniques and population data from 1900 to 1980 for states in the United States. We find that in most instances there is a linear or nearly linear relationship between forecast accuracy and the length of the forecast horizon, but no consistent relationship between bias and the length of the horizon. We believe that these results provide useful information regarding the nature of population forecast errors.     

城乡生源与大学毕业生初职就业机会获得

大学毕业生就业问题已经受到广泛的关注,但已有研究对城乡生源可能的影响论述并不充分;不仅直接的研究很少,而且很多研究简单在城乡混合样本中比较城乡差异。本研究通过“解决农村生源毕业生就业难问题跟踪调查研究”的数据表明：城乡生源是大学毕业生就业中可能存在的不平等,但是对这一不平等的研究不能局限于城乡生源之间的简单比较,而应该更为重视城乡生源大学生可能并不完全相同的就业机制。本研究发现,尽管城乡混合模型中,城乡生源变量的影响并不显著;但是分别对城市生源样本和农村生源样本拟合模型后,性别、专业、兼职次数、是否党员以及家庭背景等多个变量对大学毕业生就业的影响在城乡生源样本中出现了不同。     

An efficient two-stage randomized response model under stratified random sampling

A two-stage randomized response model is extended to stratified random sampling in order to find out more efficient estimators of proportions built from sensitive questions, which respondents may not answer truthfully, in a population divided into homogeneous subgroups. In each subgroup, the respondents who have not answered the sensitive question in the first stage are requested in the second stage to either answer the sensitive question (second attempt then) or to draw a card indicating “yes” or “no”. In the latter case, they are required to report the outcome. Such extension provides a more efficient estimator of the proportion of the population having a given sensitive attribute than its counterpart in simple random sampling. The extended two-stage randomized response model is more efficient than the stratified randomized response model, where respondents must answer the sensitive question either in the first or in the second stage. Moreover, it increases the respondents’ cooperation. When strata weights are unknown, they are estimated by the double sampling method.     

Social status inconsistency and migration

We use NLSY79 panel data to extend the line of sociological research encouraged in the early work of Lenski by analyzing the effects of social status inconsistencies on the likelihood and direction of migration. Given that migration is often viewed as a way for individuals to locate prospective returns fitting for their qualifications, analysis of migration behavior offers an opportunity to examine the impact of status inconsistency. Key findings indicate that under-rewarded individuals, specifically relatively highly educated individuals in low status and low paying occupations, are more likely to migrate than are status consistent individuals. Over-rewarded individuals are less likely to migrate. These findings vary across metropolitan and nonmetropolitan places: individuals in nonmetropolitan areas who are under-rewarded or have mixed statuses have higher odds of migration than status consistent respondents. Individuals in metropolitan areas with inconsistent statuses are not more likely to migrate than status consistent respondents once other determinants of migration are entered in the analysis. Exploratory analysis shows migration increases the likelihood of achieving status consistency. Further examination of the interrelationship between migration and status inconsistency is recommended.     

Working and caring for large families: do mothers face a trade-off?

Does having three or more children lower the chance that mothers participate in the labour force compared to those who have two children? Most of the previous literature on this topic describes the substantial indirect costs of children for first-time mothers, but having additional children at higher parities can entail even higher indirect costs. This paper finds a labour force participation gap between mothers who have three or more children and those who have two children. It explores whether this gap is caused by the selectivity of those who purposely choose to have large families or by family size itself. It also questions if the gap occurs simply because mothers with 3 or more children are consequently more likely to care for young children: 42?% of them have a child under the age of five compared to only 38.7?% of mothers with 2 children. A priori, it is unclear if the employment gap between these two groups of mothers is driven by the difference in the age of the youngest child or by the difference in the number of children. This paper contributes to the literature by disentangling the effect of having an additional child from having an additional young child in the household with a simple but innovative approach (grouping by mother??s age and her age at the second pregnancy) that avoids controlling for the age of the youngest child in regression.     

Deprivation index for small areas in Spain

The term deprivation is often used to refer to economic or social shortages in a given geographical area. This concept of deprivation has been identified for years using simple indicators such as income level, education and social class. One of the advantages of using simple indicators is the availability of data, since they come directly from sources of information like censuses and population registers. However, the main disadvantage of these indicators is their limited usefulness when measuring a concept as complex as deprivation with a single variable. One possible solution to this problem is using compound indices, made up of a combination of simple indicators. For years, the concept of material deprivation in Spain has been measured using indices or indicators imported from other countries. However, there are no studies that investigate if all of these variables are really related to material deprivation in Spain. In this context, the objective of this study is to create a synthetic index for material deprivation for the municipalities in Spain, bearing in mind the variables available from the Population and Housing Census. The index was built on a principal components factor analysis. The analysis showed two factors. The first factor showed a high positive correlation to the variables relating to illiteracy rate, unemployment rate and percentage of manual labourers, while the second factor was seen as highly positively correlated to the variables relating to the percentage of homes without access to a vehicle and the dependency index and also correlated, though negatively, to the percentage of foreigners between 16 and 49 who lived abroad in 1991. The variables that make up the first factor can be considered to be an approximation of the concept of deprivation in Spain. This study proposes a deprivation index made up of three simple indicators available from national information sources: percentage of illiteracy, percentage of unemployment and percentage of manual labourers. With this index, the criteria for measuring deprivation in Spanish municipalities can be unified and a comparison of the results of the different studies in our context facilitated.     

“Allow access to location?”: Digital feminist geographies

Abstract

This article looks at the impacts ongoing processes of digitization have on feminist politics of location. It argues that, rather than being borderless by nature, the digital has to be understood as producing different kinds of borders, demanding different kinds of politics of location. New potentialities arise with the challenge of creating a politics fitting to the current mode in which locations become slippery. Discussing the emergence of cyberfeminism in the early 1990s and a more recent example of digital feminism—the #SolitarityIsForWhiteWomen hashtag—this article thinks through the following questions: what does the “cyborg” as a posthuman (and postgender) category have to offer for those who have been (and are) excluded from the notion of the “human”? More specifically, how can we understand and conceptualize the “cyborg” beyond triumphalist narratives of being beyond difference?     

Estimation of adult mortality using forward and backward projections

Summary In this paper it is shown that, contrary to our intuitive understanding of the nature of population projection, the estimation of adult intercensal mortality leads to different results depending on whether forward or backward projection of the population is used. From this result a simple procedure is developed that yields estimates of the completeness of adult mortality registration. Finally, the nature and performance of a variety of methods that have recently been developed to estimate adult mortality in the absence of accurate data are compared.     

Akinetic model of population dynamics

The relations between fertility, mortality, growth rate and age distribution in closed populations have been derived by means of a set of differential equations based on the well known theory of chemical kinetics. The classical relations for stable populations are easily obtained in this model by simple algebraic manipulations. A rough but useful further simplification is to divide the population into three groups—pre-reproductive, reproductive, and post-reproductive. For this three-group model simple algebraic expressions connect fertility, mortality, growth rate and the fractions of the population in each group. Although the relations obtained are not precise, they serve to illustrate simply and directly the interactions among the basic population variables.     

A method for the estimation of fecundability

A new method for the estimation of the mean and variance of fecundability is described. The data input required for this procedure is the distribution of the interval from marriage to first birth, or from the resumption of the conception risk after contraction to the subsequent birth. The estimates of the mean and variance of fecundability are obtained by fitting a model to the observed interval distribution. To test the method, it is applied to data from five historical populations. The fecundability means in these populations ranged from 0.18 to 0.31 while the co-efficients of variation all had values near 0.56. A short method for the estimation of the mean of fecundability based on the same model, but not requiring a computer, is also presented.     

Happiness in Canada Since World War II

Where data exist, measures of averagehappiness in industrialized countries typicallyshow little or no upward trend over time,despite substantial growth in real per capitaincomes. This paper examines the existingCanadian data to see if they support thisgeneralization. The Canadian data have someoverall positive trend. Some simple regressionssuggest that per capita real incomes arepositively associated with happiness, whileunemployment and inflation appear to benegatively associated with happiness, a resultalso found in recent studies of Western Europeand the United States. Controlling for thesevariables, a negative time trend emerges.     

Estimating demographic characteristics using the ratio-correlation method

Studies of the relative accuracy of methods of estimating the population at the substate level have generally found that the greatest degree of accuracy is provided by the ratio-correlation, or regression, method. This paper reports on research aimed at evaluating the effectiveness of this method in estimating the age and race composition of populations at the substate level. In addition to the basic multiple regression equation, variants such as stratification and the averaging of estimates from simple regression equations are also tested. Surprisingly, for Virginia localities the most satisfactory results are generated by the nonstratified multiple regression equation.     

The heterogeneity of ethnic employment gaps

This paper investigates the heterogeneity of ethnic employment gaps using a new single-index based approach. Instead of stratifying our sample by age or education, we study ethnic employment gaps along a continuous measure of employability, the employment probability minority workers would have if their characteristics were priced as in the majority group. We apply this method to French males, comparing those whose parents are North African immigrants and those with native parents. We find that both the raw and the unexplained ethnic employment differentials are larger for low-employability workers than for high-employability ones. We show in a theoretical framework that this heterogeneity can be accounted for by homogeneous underlying mechanisms and is not evidence for, say, heterogeneous discrimination. Finally, we discuss our main empirical findings in the light of simple taste-based vs. statistical discrimination models.     

A theoretical analysis of antecedents of young couples’ fertility decisions and outcomes

Longitudinal survey data from 509 couples who at Time 1 interview had recently married or had their first child did not support the hypothesis that demographic factors influence fertility intentions, decisions, and outcomes only indirectly through their effects on attitudes and motivations. Husbands’ and wives’ attitudes exerted reciprocal influence on one another. However, while husbands’ sex-role traditionalism and motivation for parenthood strongly influenced wives’ traditionalism and motivation in the case of recently married couples, this pattern was reversed for riew parents. Birth control use was directly affected by wives’ fertility intentions, but not by husbands’ intentions. Difficulties in examining couple interaction variables such as relative power and the possible limitations of fitting these data to a complex theoretical model using LISREL are discussed.     

The economic explanation of fertility changes in the United States

Abstract It is widely assumed that fertility varies positively with economic conditions. Actually this assumption receives little support from the historical record. For a century before 1930 fertility declined while the economy expanded and real incomes rose. Then for nearly three decades fertility and incomes fell and rose together. Since 1960 they have again moved in opposite directions. Clearly, no simple generalization about their relation will hold water. More sophisticated explanations are based on relative rather than absolute incomes. Banks suggested that the downturn in English fertility in the 1870's might have occurred because standards of middle-class consumption rose faster than middle-class incomes, but he found the evidence inconclusive. To reconcile the post-war baby boom in the United States with earlier experience, Easterlin has argued that fertility is determined by the relationship between the income of couples in their twenties and the income of their parents ten to fifteen years earlier. Among the weaknesses of this theory as applied to U.S. experience are its failure to explain the sharp drop in fertility, including that of native white urban women, in the 1920's; the fact that fertility rose most in the baby boom at the higher socio-economic levels where incomes rose least; and the sharp decline of fertility after 1962 in spite of the favourable trend of incomes, including those of younger people. The broad conclusion is that while couples no doubt do consider income, employment opportunities, etc. in deciding how many children to have, such considerations have had a relatively minor influence on changes in fertility, which for the most part have been the result of changes in attitudes. Even the post-war baby boom was a result not only of higher incomes and full employment but also of a shift in attitudes toward family size, particularly among the better-educated, economically better-off sections of society.