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Results for “Demographic modelling”

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PubMed1996

Improving the AAPCC (adjusted average per capita cost) with health-status measures from the MCBS (Medicare Current Beneficiary Survey).

Using data from the 1991 Medicare Current Beneficiary Survey (MCBS), multiple regression-based models predicting 1992 Medicare costs are developed and compared. A comprehensive model incorporating demographic, diagnostic, perceived health, and disability variables is shown to be stable and to fit the data well over the full range of Medicare-covered annual per capita expenses and for a variety of beneficiary subgroups defined by their health and functional status. This model produces stable unbiased estimates of expenditures on validation samples. A variant of this model is being considered for use in setting Medicare capitation payments for the second phase of the social/health maintenance organization (S/HMO) demonstration.

Activities of Daily Living↗

PubMed2000

Combining registration-system and survey data to estimate birth probabilities.

With the widespread availability of event-history data, demographers have increasingly eschewed registration-system data in favor of survey data. We propose instead using survey and registration-system data in combination, via a constrained maximum-likelihood framework for demographic hazard modeling. As an application, we combine panel survey data and birth registration data to estimate annual birth probabilities by parity. The general fertility rate obtained from registration-system data constrains the weighted sum of parity-specific birth probabilities. The variances about the parity-specific birth probabilities are halved when registration-system data are used to constrain the estimates. Other demographic applications are discussed.

Adolescent↗

PubMed2003

Historical demography and genetic structure of sister species: deermice (Peromyscus) in the North American temperate rain forest.

To investigate the evolutionary and biogeographical history of Peromyscus keeni and P. maniculatus within the coastal forest ecosystem of the Pacific Northwest of North America, we sampled 128 individuals from 43 localities from southeastern Alaska through Oregon. We analysed mitochondrial DNA variation using DNA sequence data from the mitochondrial cytochrome-b (cyt-b) gene and control region, and we found two distinct clades consistent with the morphological designation of the two species. The sequence divergence between the two clades was 0.0484 substitutions per site for cyt-b and 0.0396 for the control region, suggesting that divergence of the two clades occurred during the middle to late Pleistocene. We also examined the historical demography of the two clades using stepwise and exponential expansion models, both of which indicated recent rapid population growth. Furthermore, using the program migrate we found evidence of migration from populations north of the Fraser River (British Columbia) to the south in both clades. This study demonstrates the utility of these model-based demographic methods in illuminating the evolutionary and biogegographic history of natural systems.

Animals↗

PubMed2005

Factors that contribute to child maltreatment severity: a multi-method and multidimensional investigation.

OBJECTIVES: This study used data gathered during evaluations conducted by the Comprehensive Assessment and Training Services (CATS) Project to determine the relative contribution of four primary domains (demographic, adult characteristics, child characteristics, relational characteristics) to variation in the severity of child maltreatment, and to facilitate the development of empirically-based risk assessment tools. METHODS: A multidimensional, multi-method approach to data collection was used to assess 208 maltreating parents. Hierarchical multiple regression analyses were performed by entering each domain of variables into the regression equation in four consecutive blocks. RESULTS: The results of this study suggest that maltreatment severity varies as a function of the level of trauma recovery, substance misuse, a child's externalizing behavior, and qualitative features of the parent-child relationship, as well as the level of family stress. Relationship variables added to the amount of variance accounted for in the overall model, beyond demographic, adult, and child variables. CONCLUSIONS: : The findings of this study call attention to the importance of developing a multidimensional assessment model of the factors leading to child maltreatment severity and to broadening the parameters of assessment models used in child maltreatment research. The role that each of the contributing factors plays in the interference of effective parenting is also discussed.

Causality↗

PubMedDate not supplied

A causal approach to the study of fertility and familism.

This paper tests, within the framework of LISREL, the causal structures of fertility using data from the 1973-74 Growth of Alberta Family Study (GAFS) of women aged 18-44 who are currently married or living common-law. Differential fertility among two groups of women classified by nativity also are examined. The women's background characteristics (e.g., age, religiosity, and education) are viewed as exogenous variables. The endogenous variables are familism and expected family size; familism is designated as an intermediate variable in the model, linking demographic and socioeconomic (including cultural) factors to fertility, The results indicate that familism acts as an important variable explaining fertility, particularly, among foreign-born women. The study confirms and extends earlier research findings that religiosity and education influence couples' fertility, the former positively and the latter negatively.

Adolescent↗

PubMed1999

Modeling risk using generalized linear models.

Traditionally, linear regression has been the technique of choice for predicting medical risk. This paper presents a new approach to modeling the second part of two-part models utilizing extensions of the generalized linear model. The primary method of estimation for this model is maximum likelihood. This method as well as the generalizations quasi-likelihood and extended quasi-likelihood are discussed. An example using medical expense data from Washington State employees is used to illustrate the methods. The model includes demographic variables as well as an Ambulatory. Care Group variable to account for prior health status.

Adolescent↗

PubMed2005

Temporal autocorrelation can enhance the persistence and abundance of metapopulations comprised of coupled sinks.

In spatially heterogeneous landscapes, some habitats may be persistent sources, providing immigrants to sustain populations in unfavorable sink habitats (where extinction is inevitable without immigration). Recent theoretical and empirical studies of source-sink systems demonstrate that temporally variable local growth rates in sinks can substantially increase average abundance of a persisting population, provided that the variation is positively autocorrelated--in effect, temporal variation inflates average abundance. Here we extend these results to a metapopulation in which all habitat patches are sinks. Using numerical studies of a population with discrete generations (buttressed by analytic results), we show that temporal variation and moderate dispersal can jointly permit indefinite persistence of the metapopulation and that positive autocorrelation both lowers the magnitude of variation required for persistence and increases the average abundance of persisting metapopulations. These effects are weakened--but not destroyed--if variation in local growth rates is spatially synchronized and dispersal is localized. We show that the inflationary effect is robust to a number of extensions of the basic model, including demographic stochasticity and density dependence. Because ecological and environmental processes contributing to temporally variable growth rates in natural populations are typically autocorrelated, these observations may have important implications for species persistence.

Ecosystem↗

PubMed1990

Changes in drinking behavior: demographic, psychosocial, and biomedical factors.

Demographic, psychosocial, and biomedical variables were collected from 12,371 ambulatory persons who had an initial multiphasic health examination in 1978 or 1979 and a second examination 5 years later in 1983 or 1984. Subgroups of this cohort who had substantially increased and decreased their drinking were compared with persons who continued to drink at baseline rates. A balanced model of demographic, psychosocial, and biomedical variables had the capacity to differentiate persons who had substantially increased their drinking; fewer variables--primarily psychosocial--differentiated persons who had greatly decreased their drinking.

Adult↗

PubMed1990

[From twentieth to twenty-first century: Europe and its population after the year 2000].

The model of demographic transition predicts that in the final stages of the transition, the population will become stationary. However, during the past 20 years or so, the birth rate in the majority of industrialized countries has fallen below the death rate, and a continuation of this trend will ultimately result in a declining population. In the UN recent projections of world population growth, an attempt was made to salve the transition model by assuming that when faced with a reduction in numbers, couples will wholeheartedly respond by increasing their family size. The author presents a theoretical model in which he showed that during the final stages of the transition, it is likely that there are built-in mechanisms which will result in low birth rates, and that it is unlikely that fertility will return to replacement level. In addition to the scenario presented by the UN, there is another in which the birth rate remains below the death rate indefinitely. This catastrophic scenario would ultimately result in the disappearance of the human species. The author presents and compares both of these scenarios. Using some calculations by J.N. Biraben, he calculates the number of humans that would have been born between the beginning and end of the human species, as described by the catastrophic scenario and estimates this to be at 100 billion. In order to end on a more upbeat note, he than imagines a new demographic transition in which biologists have succeeded in extending the duration of a woman's reproductive life. They could then engage in 2 fertile unions during their lifetimes and thus save the species.

Birth Rate↗

PubMedDate not supplied

Demographics, not beverage consumption, is associated with diet quality.

BACKGROUND: Demographic characteristics and beverage choices may affect diet quality. OBJECTIVE: To estimate the independent associations between consumption of food categories of the US Department of Agriculture Food Guide Pyramid, beverage consumption, gender, age, family income, and race/ethnicity with the Healthy Eating Index (HEI). METHODS: Data from the Continuing Survey of Food Intake by Individuals 1994-96, 1998 were used to develop multiple regression models of demographics and food and beverage consumption regressed on the HEI. RESULTS: After adolescence (13-19 years), males consistently had a lower diet quality than females. Young adults (20-29 years) had the poorest diet quality. Family income had a positive association with the HEI. Controlling for income, African-Americans had lower HEI scores than other race/ethnicity groups. Caucasians consumed significantly more milk products than did the other race/ethnicity groups. Consumption of beverages had a weak but positive association with the HEI. CONCLUSIONS: Family income and race/ethnicity have unique and independent associations with the HEI and dietary patterns.

Adolescent↗

PubMed2026

Antidepressant use among American adults in a 50-state survey.

BACKGROUND: Antidepressants are among the most prescribed medications in the USA, yet challenges in access to mental health treatment persist. OBJECTIVE: To assess current and lifetime antidepressant and psychotherapy use among American adults, and examine attitudes towards potential federal restrictions on antidepressant prescribing. METHODS: We conducted a cross-sectional survey study using data from a national non-probability internet-based panel weighted to approximate national demographics (age, gender, race and ethnicity, education, US census region, and urbanicity) based on 2020 US Census data. Data were collected between 10 April and 27 May 2025 from 30 810 adults residing in the USA. The primary outcomes were self-reported current and past antidepressant and psychotherapy use, and support for or opposition to potential federal restrictions on antidepressant prescribing. Logistic regression models estimated demographic and treatment-related features associated with these outcomes. FINDINGS: Among 30 115 respondents with complete antidepressant data, 16.6% reported current antidepressant use, and of 30 098 respondents with psychotherapy data, 10.4% reported current psychotherapy. Use of both treatments was significantly greater among White respondents compared with all other racial groups. When asked about potential federal restrictions on doctors prescribing antidepressants, 16.4% of respondents supported and 48.0% opposed such regulation, with lesser opposition among those of male gender (OR 0.69, 95% CI 0.65 to 0.73), and greater opposition among those with lifetime antidepressant treatment (OR 2.37, 95% CI 2.21 to 2.54). CONCLUSIONS: Antidepressant and psychotherapy use remains unevenly distributed across demographic groups. A significant proportion of adults in every US state oppose efforts to restrict access to antidepressant prescribing, reflecting broad public support for maintaining access to treatment. CLINICAL IMPLICATIONS: Findings from this study suggest that restrictive policies on antidepressant prescribing are unlikely to align with public sentiment and may risk exacerbating existing inequities in care.

Humans↗

PubMed1989

[Proposal for a model for the desaggregation of demographic projections of large areas into their geographical components].

The problem of the preparation of estimates of the total population of geographic subdivisions after the 1980 census is studied with a view to the tabulation on mortality data of Rio de Janeiro State (Brazil) by municipal districts and the estimation of regional mortality rates. In Brazil, the calculation of the official population estimates is undertaken by the Brazilian Institute of Geography and Statistics. The method employed to estimate the population of geographic subdivisions is known as the "AiBi method". This procedure is analysed and an alternative mathematical model is proposed that also satisfies the closure condition, that is, the projected values for the sum of the segments up to the total population projection. As an application of the proposed model, estimates of the population of the municipal districts of Rio de Janeiro State were prepared covering the period from 1981 to 1990.

Brazil↗

PubMed1985

[Basic theoretical and methodological principles of developing a population and housing census program in the People's Republic of Bulgaria in 1985].

"Proceeding from the Marxist approach to the relation between population and social development, a significantly broader theoretical model of studying the population by means of the forthcoming [Bulgarian] census is justified." The model includes demographic, educational, and socioeconomic aspects, as well as labor force activity. The collection of data by means of sample surveys is assessed, with a focus on areas concerning fertility and reproductive behavior, migration, labor needs and resources, health, and the social system. (summary in ENG, RUS)

Bulgaria↗

PubMed1990

A multivariate analysis of adolescents' orientations toward physician use.

Health professionals know surprisingly little about the origins of the health beliefs and orientations they often seek to change, and they do not know about when, or if, changes in these orientations are likely to occur. This study is aimed at increasing our understanding of the origins and development of health beliefs and attitudes by focusing on the impact of parents' orientations toward physician utilization (inclination to consult a doctor when experiencing somatic symptoms) on the comparable orientations of their adolescent children. Hypotheses regarding direct parent-adolescent links are examined within a multivariate structural equations model relating demographics, adolescents' interpersonal competencies, and parental variables to adolescents' orientations toward physician utilization. Evidence for the development of these orientations is obtained by comparing influences across two groups of adolescents: 12- to 13-year-olds and 16- to 18-year-olds. Findings indicate that adolescents' orientations toward physician use are associated with those of their parents and that this link is generally stronger and more specific during late adolescence. The model also suggests that these orientations conform to social and cultural variables related to differences in social stratification.

Adolescent↗

PubMed1988

The transmission dynamics of human immunodeficiency virus (HIV).

The paper first reviews data on HIV infections and AIDS disease among homosexual men, heterosexuals, intravenous (IV) drug abusers and children born to infected mothers, in both developed and developing countries. We survey such information as is currently available about the distribution of incubation times that elapse between HIV infection and the appearance of AIDS, about the fraction of those infected with HIV who eventually go on to develop AIDS, about time-dependent patterns of infectiousness and about distributions of rates of acquiring new sexual or needle-sharing partners. With this information, models for the transmission dynamics of HIV are developed, beginning with deliberately oversimplified models and progressing--on the basis of the understanding thus gained--to more complex ones. Where possible, estimates of the model's parameters are derived from the epidemiological data, and predictions are compared with observed trends. We also combine these epidemiological models with demographic considerations to assess the effects that heterosexually-transmitted HIV/AIDS may eventually have on rates of population growth, on age profiles and on associated economic and social indicators, in African and other countries. The degree to which sexual or other habits must change to bring the 'basic reproductive rate', R0, of HIV infections below unity is discussed. We conclude by outlining some research needs, both in the refinement and development of models and in the collection of epidemiological data.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Contraceptive self-efficacy in college women.

We examined the relationship between the theory of self-efficacy and its effect on contraceptive use along with other variables in a predominantly white female college population. Written survey questionnaires were administered to 356 subjects in college classrooms; the study sample was limited to those 250 female subjects who were age 17-25 years unmarried, and sexually active. The questionnaire was designed to measure contraceptive use, contraceptive self-efficacy, demographic variables, and other variables associated with the college psychosocial environment (i.e., alcohol use, history of sexual assault, and future orientation in education and career plans). Contraceptive self-efficacy (CSE) was highly correlated with effective use (r = .4, p < 0.01). Highly effective contraceptive users had a significantly higher mean CSE score (p < 0.01) than that of less effective users. Logistic regression analysis of effective contraceptive use resulted in a four-factor model that correctly classified 76.3% of users. Contraceptive self-efficacy was the most important predictor of contraceptive use for this sample. Lack of barriers to contraception was also important, with knowledge and length of time of sexual activity also included in the final regression model. Most demographic and future orientation variables were not significantly associated with effective use; variables measuring sexual experience and personal attitudes and perceptions about birth control were more significantly associated with effective use. A lack of interference from alcohol was highly associated with effective contraceptive use. Self-efficacy would seem to be important in predicting contraceptive use and effecting behavior change.

Adolescent↗

PubMed1997

Genetic drift and gene flow in post-famine Ireland.

This study examines the genetic impact of the Great Famine (1846-1851) on the regional genetic structure of Ireland. The Great Famine resulted in a rapid decrease in population size throughout Ireland in a short period of time, increasing the possibility of genetic drift. Our study is based on migration and anthropometric data collected originally in the 1930s from 7211 adult Irish males. These data were subdivided into three time periods defined by year of birth: 1861-1880, 1881-1900, and 1901-1920. Within each time period the data were further subdivided into six geographic regions of Ireland. Estimates of Wright's FST were calculated from parent-offspring migration data and from 17 anthropometric variables (10 head measures, 7 body measures). Over time, the average population size decreased, but average rates of migration increased. The estimates of FST at equilibrium from migration matrix analysis suggest that the net effect of these opposite effects is a reduction in among-group variation. Closer examination shows that within each time period the rate of convergence to equilibrium is slow, meaning that the expected levels of genetic homogeneity revealed from migration matrix analysis are not likely to be seen over short intervals of time. Estimates of FST from anthropometric data show either relatively little change in microdifferentiation or some increase, depending on which variables are analyzed. Investigation of a simple model of demographic and genetic change shows that, given the demographic changes in post-Famine Ireland, FST could in theory increase, decrease, or remain the same over short intervals of time. Overall, the Great Famine appears to have had minimal impact on the genetic structure of Ireland on a regional level. Comparison with studies focusing on local genetic structure shows the opposite. It appears that the level of genetic impact depends strongly on the level of analysis; local populations are affected to a greater extent by demographic shifts than regional populations. We also provide formulas for the standard errors of FST from metric traits and related statistics.

Adolescent↗

PubMedDate not supplied

Psychosocial and demographic factors related to health behaviors in the 1st trimester.

OBJECTIVE: To explore the relationship of psychosocial and demographic variables to health behaviors in early pregnancy. DESIGN: First trimester findings presented from a prospective study of weight gain in pregnancy. SETTING: A comprehensive health care system in central Texas. PARTICIPANTS: 114 pregnant women (75% white, 13% African American, 10% Hispanic, 2% Asian) of 12 weeks gestation or less. OUTCOME MEASURE: Self-Care Inventory, which includes diet/eating, substance abuse, recklessness, hygiene-related practices, sleep/rest, and exercise behaviors. RESULTS: In regression analysis the final model of demographic and psychosocial variables showed that higher depressive symptoms, lower internal locus of control for fetal health, and lower family income were related to poorer health behaviors in the 1st trimester of pregnancy. CONCLUSIONS: Health behaviors in early pregnancy may be affected by psychosocial factors such as depressive symptoms. Greater emphasis should be given to such factors in research and prenatal assessments.

Adolescent↗