Promises and Pitfalls of Using Digital Traces for Demographic Research

The digital traces that we leave online are increasingly fruitful sources of data for social scientists, including those interested in demographic research. The collection and use of digital data also presents numerous statistical, computational, and ethical challenges, motivating the development of new research approaches to address these burgeoning issues. In this article, we argue that researchers with formal training in demography—those who have a history of developing innovative approaches to using challenging data—are well positioned to contribute to this area of work. We discuss the benefits and challenges of using digital trace data for social and demographic research, and we review examples of current demographic literature that creatively use digital trace data to study processes related to fertility, mortality, and migration. Focusing on Facebook data for advertisers—a novel “digital census” that has largely been untapped by demographers—we provide illustrative and empirical examples of how demographic researchers can manage issues such as bias and representation when using digital trace data. We conclude by offering our perspective on the road ahead regarding demography and its role in the data revolution.     

Fear of crime and behavioral restrictions in urban and suburban neighborhoods

Variations in fear of crime and behavioral restrictions were explored within city and suburban neighborhoods of the Chicago metropolitan area. A random telephone survey (n=1,803) gathered information on fear and behavioral restrictions, other crime-related experiences and perceptions, perceptions of the neighborhood physical and social environment, and demographic characteristics. These data were supplemented by merging contextural information (from census and other archival sources) about each respondent's place of residence to the data set. Hierarchial step-wise regression analyses were performed separately for the city and suburban residents. Sets of predictor variables were found that accounted for more than 25 percent of the variance in the criterion measures. Implications of these findings for policy makers and future research are discussed.     

The US Decennial Census: Political Questions,Scientific Answers

The US decennial census was initiated in 1790 to facilitate nation‐building tasks, especially that of reconfiguring political representation as the population grew and settled new territories. To this basic task of power distribution have been added other key governmental functions, such as the use of census data in guiding revenue sharing and in the enforcement of nondiscriminatory policies. Throughout its history the census has been the focus of partisan clashes. Following the identification of the “differential undercount” a measure of how census coverage differs across demographic groups and geographic areas–the partisan battles intensified, and in recent decades have come to focus not just on how the census counts are used but how the census data are collected. It has been argued that census methodology could be designed to predetermine given partisan outcomes, and for the 2000 census this charge shifted from “could be” to “is.” The Census Bureau has taken extraordinary steps to demonstrate that no partisan considerations have affected the design or implementation of the census, and that its decisions are based solely on the best technical judgment available.     

The business of demographics

The emergence of "demographics" in the past 15 years is a vital tool for American business research and planning. Tracing demographic trends became important for businesses when traditional consumer markets splintered with the enormous changes since the 1960s in US population growth, age structure, geographic distribution, income, education, living arrangements, and life-styles. The mass of reliable, small-area demographic data needed for market estimates and projections became available with the electronic census--public release of Census Bureau census and survey data on computer tape, beginning with the 1970 census. Census Bureau tapes as well as printed reports and microfiche are now widely accessible at low cost through summary tape processing centers designated by the bureau and its 12 regional offices and State Data Center Program. Data accessibility, plummeting computer costs, and businessess' unfamiliarity with demographics spawned the private data industry. By 1984, 70 private companies were offering demographic services to business clients--customized information repackaged from public data or drawn from proprietary data bases created from such data. Critics protest the for-profit use of public data by companies able to afford expensive mainframe computer technology. Business people defend their rights to public data as taxpaying ceitzens, but they must ensure that the data are indeed used for the public good. They must also question the quality of demographic data generated by private companies. Business' demographic expertise will improve when business schools offer training in demography, as few now do, though 40 of 88 graduate-level demographic programs now include business-oriented courses. Lower cost, easier access to business demographics is growing as more census data become available on microcomputer diskettes and through on-line linkages with large data bases--from private data companies and the Census Bureau itself. A directory of private and public demographic resources is appended, including forecasting, consulting and research services available.     

迁入地类型的选择——基于五普资料的分析

利用第五次人口普查长表0.95‰微观资料,研究移民特征对迁入地类型选择的影响。结果显示,移民的人口因素和社会特征对迁移目的地的选择有较大的影响。移民人口有向青壮年集中的趋势。婚姻迁移妇女的目的地主要是乡村。有配偶的人更多地考虑迁移对家庭的影响。户籍制度仍然对人口迁移起到限制作用。     

AN INVESTIGATION OF GENERALIZED RAKINGIN THE SYNTHETIC ESTIMATION OFPOPULATION SIZE

The problem of counting a population that is cross-classified with respect to demographic and geographic attributes is considered. A census is conducted in which individuals are “captured” with probabilities that are believed to be relatively constant within demographic categories. The census is followed by a random sample in which individuals are “recaptured” independently of the census. Using the two counts, capture-recapture estimates of the demographic category populations are obtained. A synthetic estimate of population size for a geographic entity is obtained by summing the corresponding adjustment factors (capture-recapture estimates divided by census counts) across all individuals captured by the census in the entity. The use of generalized raking is considered as a method for smoothing adjustment factors. It is found that generalized raking differs little from a class of weighted least squares regression models. This suggests that generalized raking does not offer an improvement over regression for smoothing adjustment factors. The efficiency loss of generalized raking relative to the best regression-based procedures can be substantial.     

The role of demographic data in the operation of public policy: a case study of the job training partnership act

To work at the state and local levels, the Job Training Partnership Act (JTPA) requires specific kinds of demographic data. Unemployment figures, poverty information, occupational supply and demand data, wage structure, and many other types of data are used in planning and operating JTPA programs, and in modifying the performance standards by which the programs are evaluated. The decennial census provides some key data and thus some significant types of information become less timely as the decade progresses. Furthermore, the framers of the Act had little or no knowledge of the forms in which data are collected and thus definitions given in the Act do not always agree with definitions used in the demographic data which are available. The policymakers for future government benefit programs could learn from this mistake: before writing legislation which is so heavily dependent on demographic data, they should ascertain what types of data are available or can be generated for use in the program.     

Examination of the generalized age distribution

The formula for the age distribution and other relationships that follow from it for any (non-stable) population presented by Preston and Coale are significant contributions to demography. The formulas summarize the relationships among various demographic measures precisely, and are formally analogous to the relationships that hold for stable populations. The significance of these formulas cannot be overstated; they allow us to understand clearly the relationships among demographic measures in any arbitrary population. However, when it comes to using them for estimating demographic measures when census data are defective, the method of estimation is still affected by defective data. The reason is that the series of age-specific growth rates reflects the observed census age distributions exactly so that any defects in the census data are summarized in the growth rates. This paper begins with the formulation of the discrete version of the "new synthesis" developed by Preston and Coale. With the discrete formulation, the three kinds of errors introduced when the continuous time formulas are applied to real data can be avoided. Then it is pointed out that when two accurate census data are available, the Preston-Coale procedure of "estimating" the age distribution at the second census is equivalent to checking the identity of the age distribution formula. Also "estimating" mortality by the procedure of Preston-Coale is shown to be equivalent to obtaining mortality directly from intercensal survival rates. That the procedure which involves the age-specific growth rates is equivalent to those that involve the intercensal survival rates may have escaped notice because there are no a priori constraints for patterns of age-specific growth rates to follow. The irregularity in growth rates due to defective data are not distinguishable from true irregularity that exists in the population, contrary to the well-known regularity in the pattern of survival rates in human populations.     

An overview of demographic analysis as a method for evaluating census coverage in the United States

"Since the 1950 U.S. census, demographic methods based on the fundamental balancing equation of demography have played an important role in the evaluation of the census net undercount. Application of this set of methods, called demographic analysis, results in national estimates of the net undercount for age-race-sex groups. Although results of demographic analysis are readily available in Bureau of the Census publications, the procedures used to estimate each of the components of population change are less well-known. In this paper we review the historical foundation of demographic analysis, beginning with Coale's 1950 census evaluation project and concluding with the recent evaluation of the 1990 census. We examine each of the components of the method, how their estimation has changed over time, and how they were estimated for the 1990 census."     

Reconstructing the size of the African American population by age and sex, 1930–1990

We estimate the size of the African American population in five-year age groups at census dates from 1930 to 1990 using a three-part strategy. For cohorts born after 1935, we follow the U.S. Census Bureau in using classical demographic analysis. To estimate the size of cohorts born before 1895, we use extinct-generation estimates. For remaining cohorts, we implement an age/period/cohort model of census counts. All approaches are applied to a data set in which the age distribution of deaths has been corrected for age misreporting. Results provide strong confirmation of the basic validity of Census Bureau estimates of census undercounts for African Americans while extending estimates to new cohorts and periods. Our estimates are less consistent with an historical series prepared by Coale and Rives (1973).     

Comment on ‘minority status and family size: A comparison of explanations’ by R. Jiobu and H. Marshall

Demographers traditionally have paid little attention to tests of significance. This neglect presumably carried little risk so long as analyses used full-count census data or vital statistics data (typically with very large numbers) and as long as inter-group differences in demographic variables were larger than they are in many contexts to-day.² For a variety of reasons, this attitude may no longer be justified.     

教育发展的人口学分析及纲要性政策建议——以广东基础教育发展分析为例

许多事实证明 ,教育发展分析 (包括教育规划 )充分吸纳人口学的方法 ,往往取得具有重要意义的、实用性强的结果 ;反之 ,如果在这种分析 (规划 )中 ,未利用人口学方法 ,则容易出现这样那样的盲目性。本文利用全国第五次人口普查 (广东 )资料 ,对广东基础教育发展进行了人口学的分析 ,并对广东未来基础教育发展提出了相应的政策建议。     

Bayesian population reconstruction of female populations for less developed and more developed countries

We show that Bayesian population reconstruction, a recent method for estimating past populations by age, works for data of widely varying quality. Bayesian reconstruction simultaneously estimates age-specific population counts, fertility rates, mortality rates, and net international migration flows from fragmentary data, while formally accounting for measurement error. As inputs, Bayesian reconstruction uses initial bias-reduced estimates of standard demographic variables. We reconstruct the female populations of three countries: Laos, a country with little vital registration data where population estimation depends largely on surveys; Sri Lanka, a country with some vital registration data; and New Zealand, a country with a highly developed statistical system and good quality vital registration data. In addition, we extend the method to countries without censuses at regular intervals. We also use it to assess the consistency of results between model life tables and available census data, and hence to compare different model life table systems.     

Estimating maternal mortality differentials using census data: experience in Honduras

High levels of maternal mortality in developing countries are considered a major public health problem. Over the past decade several international conferences on health have stated the necessity to reduce maternal mortality in developing countries. This is a challenge not only in terms of achieving it but also from the point of view of monitoring it. I use national population censuses to measure maternal mortality and study mortality regional differentials in Honduras, which identified maternal mortality in its most recent census. I also use standard demographic methods to evaluate the census data quality, for both population and death counts, and to evaluate the completeness and coverage of household death data.     

U.S. Family Household Momentum and Dynamics: An Extension and Application of the ProFamy Method

The classic headship-rate method for demographic projections of households is not linked to demographic rates, projects a few household types without size, and does not deal with household members other than heads. By comparison, the ProFamy method uses demographic rates as input and projects more detailed household types, sizes, and living arrangements for all members of the population. Tests of projections from 1990 to 2000 using ProFamy and based on observed U.S. demographic rates before 1991 show that discrepancies between our projections and census observations in 2000 are reasonably small, validating the new method. Using data from national surveys and vital statistics, census microfiles, and the ProFamy method, we prepare projections of U.S. households from 2000 to 2050. Medium projections as well as projections based on smaller and larger family scenarios with corresponding combinations of assumptions of marriage/union formation and dissolution, fertility, mortality, and international migration are performed to analyze future trends of U.S. households and their possible higher and lower bounds, as well as enormous racial differentials. To our knowledge, the household projections reported in this article are the first to have found empirical evidence of family household momentum and to have provided informative low and high bounds of various indices of projected future households and living arrangements distributions based on possible changes in demographic parameters.     

The demographic viewpoint in the vital and health statistics monographs of The American Public Health Association

The plan calls for monographs on 16 specific topics and a review volume. The specific topics include a monograph on fertility, another on marriage and divorce, and one on social and economic factors in mortality, all of which are of obvious demographic interest. The core of the development of the monographs dealing with the disease topics, and accidents, homicide, and suicide, is a tabulation program involving specific and age-adjusted death rates based upon the deaths in the United States for the three year period 1959-61 and the 1960 census of population. The program called for a set of standard tabulations common to each monograph and also a set of special tabulations tailored to meet the particular needs for each topic as specified by its authors. This wealth of demographic detail regarding mortality in the United States during 1959-61 fills only one aspect of its health picture. To fill out the health picture, use is being made of the great volume of morbidity data out of the National Health Interview and Examination Surveys and a wide variety of other specialized surveys. In all of these, the findings are invariably described in terms of the demographic characteristics of age and sex, and frequently in terms of such social-economic variables as education, income, work status, and occupational class.A large part of the content of the monograph on social and economic factors in mortality will come out of available results of the 1960 census-death certificate matching study at the University of Chicago. One important feature of this monograph, not contained in the Chicago study, is a regression and correlation analysis of total mortality in 202 Standard Metropolitan Statistical Areas in relation to a large number of social, economic, and climatic factors. Among the features in the monograph on fertility are chapters on the medical and biological characteristics of births, fecundity and family planning, and an analysis of cohort fertility trends. The monograph on marriage and divorce will make use of the detailed tabulations from the 1960 census on marital status in relation to education, race, parentage, earnings and other classifications of individuals and of husband and wife in married couples. It will also contain a matching study of divorce records in certain states for a short period before the census of 1960 with the returns in the census. The project is supported by a grant from the United States Public Health Service (CH 00075; formerly RG 08262). Publication will be by the Harvard University Press.     

The use of sampling in conjunction with population censuses

In Asia and the Pacific, the practice of governments is increasingly to collect information on their populations' size, age and sex composition, geographic distribution, and certain other basic demographic and socioeconomic characteristics on the basis of a complete (100%) enumeration, and to supplement this basic information by collecting information on a larger range of variables on a sample basis. The additional information, which is gathered as part of the census operation, may be related to such population characteristics as migration, employment, fertility, and health. A complete census is generally indispensable for obtaining information about small domains, and also for obtaining politically important data, which must be seen to be free from sampling variability. A complete census is typically confined to obtaining a detailed picture of the number and basic structural characteristics of the entire population, with as much detail as possible about local areas. Sample surveys can quickly obtain a wider variety of more complex data. Sampling applications for the census include 1) using sampling in the design and control of census operations, such as in planning, testing, controlling, and evaluating the census; 2) using sample enumeration to supplement items covered in the complete census; 3) sampling the census results for processing to make the results available more quickly and at lower cost; and 4) extracting samples of microlevel files of detailed census data so as to facilitate dissemination of primary data.     

Demographics: people and markets

The basics of demography are now basic to us business as well. Demographics combine demographic data with socioeconomic and geographic factors to help business and other managers know the market for their goods and services. This pamphlet explains market, product, and site analyses, discusses data sources and resources, and includes case studies involving major corporations. Post-war population trends have had an enormous impact on consumer and labor markets, bringing home to business the importance of taking advantage of demographic shifts. Advances in computerized access to data describing changes and increased consciousness of their economic significance has spurred the application of demographic knowledge by managers and the growth of the demographics information industry. The pamphlet describes the resources and methods of demographics including the creation and use of demographic data products.     

Comparison of Census 2000 and American Community Survey 1999–2001 Estimates: San Francisco and Tulare Counties, California

Data from the United States 2000 decennial census long form sample is compared to the U.S. Census Bureau’s fledgling American Community Survey (ACS) that was designed to replace the census long form in 2010. This article concentrates on two California counties, San Francisco and Tulare, which were part of the demonstration phase of the ACS. These counties are described and an overall comparison of the demographic, social, economic, and housing variables is presented. The project data and measures of census and survey quality such as self-response rates and nonresponse rates are displayed and discussed. Differences in the census and survey results are noted in the context of statistically significant and meaningful differences. Finally, strategies for analyzing and using ACS data are suggested.