Age-Period-Cohort models offer a useful framework to study trends of time-specific phenomena in various areas. Yet the perfect linear relationship among age, period, and cohort induces a singular design matrix and brings about the identification issue of age, period, and cohort model due to the identity Cohort = Period -- Age. Over the last few decades, multiple methods have been proposed to cope with the identification issue, e.g., the intrinsic estimator (IE), which may be viewed as a limiting form of ridge regression. This study views the ridge estimator from a Bayesian perspective by introducing a prior distribution(s) for the ridge parameter(s). Data used in this study describe the incidence rate of cervical cancer among Ontario women from 1960 to 1994. Results indicate that a Bayesian ridge model with a common prior for the ridge parameter yields estimates of age, period, and cohort effects similar to those based on the intrinsic estimator and to those based on a ridge estimator. The performance of Bayesian models with distinctive priors for the ridge parameters of age, period, and cohort effects is affected more by the choice of prior distributions. In sum, a Bayesian ridge model is an alternative way to deal with the identification problem of age, period, and cohort model. Future studies should further investigate the influences of different prior choices on Bayesian ridge models. / text

The main aim of this thesis is to analyse different mortality models regarding the longevity risk. We focus on the well-known stochastic models (Lee-Carter model, Age-period-cohort model by Renshaw and Haberman, Cairns-Blake-Dowd two-factor model) and compare them with relatively new Taiwanese model by Yang, Yue and Huang which is based on principal component analysis. Both the theoretical and also the empirical parts are included. Empirical part evaluates all the models mentioned above on the Czech mortality data from 1970-2000 for individuals aged between 50-100 years. Final mortality predictions are made for next 30 years.

Suicide is one of the major health issues and causes of mortality in modern societies. A global morality rate of suicide is 16 persons per 100,000 according to the World Health Organization report. Fortunately, the rates in most OECD countries have shown a dramatic decrease over the last 20 years. There are, however, two important exceptions, Japan and South Korea. The suicide rates in these two countries have been on an increasing trend. Because the two neighboring countries share similar socio-demographic contexts, I investigated the effects of the three time-related demographic variables (age, period, and cohort) on suicide rates in Japan and South Korea. The Age-Period-Cohort Intrinsic Estimator model was operated using data of vital statistics and population census from the Statistics Bureau and the Ministry of Internal Affairs and Communications in Japan, and cause of death data and population census from Statistics Korea in South Korea. Even though the two countries are neighboring countries that have had some similar socio-demographic contexts, the factors contributing to increasing suicide rates vary in each country. The result showed age effects in Japan greatly contributed to suicide compared to period and cohort effects, and the age effects were highest during the fifties age bracket. On the other hand, South Korea turned out to have more compound reasons, showing pronounced age effects in the elderly population, increasing period effects, and the strong cohort effects of the current elderly and middle-aged populations. From this result, although Japan and South Korea are neighboring countries with shared histories, industrial structures, social systems, and some similar demographic characteristics, the cause of increasing suicide rates in the two countries clearly varies and the efforts for preventing suicide must also vary depending on the social contexts of each country.

<p>This dissertation consists of three parts of empirical analyses investigating temporal patterns and consequences of (childhood) overweight and obesity, mainly in the United States and the People's Republic of China. Based on the China Health and Nutrition Survey, the first part conducts hierarchical age-period-cohort analyses of childhood overweight in China and finds a strong cohort effect driving the overweight epidemic. Results from the growth-curve models show that childhood overweight and underweight are related such that certain socio-economic groups with higher levels of childhood overweight also exhibit lower levels of childhood underweight. The second part situates the discussion on childhood obesity in a broader context. It compares temporal patterns of childhood overweight in China with these of adulthood overweight and finds that the salient cohort component is absent in rising adulthood overweight, which is dominated by strong period effects. A positive association between human development index and overweight/obesity prevalence across countries is also documented. Using multiple waves of survey data from the National Longitudinal Study of Adolescent Health, the third part analyzes the (latent) trajectory of childhood overweight/obesity in the United States. It finds that individuals with obesity growth trajectories are less likely to avoid mental depression, tend to have higher levels of neuroticism and lower levels of agreeableness/conscientiousness, and show less delinquent behaviors.</p> / Dissertation

This work constitutes a macro-sociological study of suicide. The empirical focus is on suicide mortality in Russia, which is among the highest in the world and has, moreover, developed in a dramatic manner over the second half of the 20th century. Suicide mortality in contemporary Russia is here placed within the context of development over a longer time period through empirical studies on 1) the general and sex- and age-specific developments in suicide over the period 1870–2007, 2) underlying dynamics of Russian suicide mortality 1956–2005 pertaining to differences between age groups, time periods, and particular generations and 3) the continuity in the aggregate-level relationship between heavy alcohol consumption and suicide mortality from late Tsarist period to post-World War II Russia. In addition, a fourth study explores an alternative to Émile Durkheim’s dominating macro-sociological perspective on suicide by making use of Niklas Luhmann’s theory of social systems. With the help of Luhmann’s macro-sociological perspective it is possible to consider suicide and its causes also in terms of processes at the individual level (i.e. at the level of psychic systems) in a manner that contrasts with the ‘holistic’ perspective of Durkheim. The results of the empirical studies show that Russian suicide mortality, despite its exceptionally high level and dramatic changes in the contemporary period, shares many similarities with the patterns seen in Western countries when examined over a longer time period. Societal modernization in particular seems to have contributed to the increased rate of suicide in Russia in a manner similar to what happened earlier in Western Europe. In addition, the positive relationship between heavy alcohol consumption and suicide mortality proved to be remarkably stable across the past one and a half centuries. These results were interpreted using the Luhmannian perspective on suicide developed in this work.

Age, period, and cohort are three temporal dimensions that can make unique contributions to social and epidemiological changes that occur in populations over time. However, while the theoretical underpinnings for each temporal dimension are well established, the statistical techniques to assess the distinctive contributions of age, period and cohort are controversial. Unless questionable assumptions are imposed on the data, traditional linear regression models are incapable of estimating the independent contribution of each temporal dimension due to the linear dependence between age, period and cohort (A=P-C). Two recently developed methods, Hierarchical Age-PeriodCohort (HAPC) and Intrinsic Estimator (IE) models, enable researchers to estimate how all three temporal dimensions contribute to an outcome of interest without resorting to such assumptions. However, some simulation studies suggest that these new methods provide biased estimates of each temporal dimension. In this dissertation, I investigated whether practitioners can avoid biased results by first understanding the structure of the data. In Chapters 2 and 3, I examined whether visual plots of descriptive statistics and model selection statistics could identify various types of data structures through a series of simulation analyses. The results showed that preliminary data analysis is useful for identifying data structures that are compatible with the assumptions of HAPC and IE models. Moreover, when the data satisfied assumptions such as three-dimensionality and slight deviations from perfect functional forms, both HAPC and IE models tended to provide unbiased estimates of age, period and cohort effects. In Chapter 4, I provided a step-by-step demonstration for applying HAPC models by investigating the unique contributions of age, period and cohort to educational inequalities in the health of a large sample of U.S. adults. This study found that age and cohort effects contribute most to variability in health, and also that cross-validation is a useful way to incorporate HAPC models when preliminary analyses do not definitively show that the data structure is three dimensional.

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Introdução: A incidência de câncer de tireóide vem aumentando em todo o mundo e não há um consenso sobre as razões deste fato. O município de São Paulo apresenta altos coeficientes de incidência desta doença, mas ainda não foi analisada sua tendência e nem sua distribuição espacial. Objetivos: Descrever os coeficientes de incidência (1997-2010) e de mortalidade (1981-2010), analisar a tendência dos coeficientes de incidência e mortalidade, segundo sexo, faixa etária, tipo morfológico (incidência), bem como os efeitos da idade, período e coorte, e examinar a distribuição espacial. Métodos: Este é um estudo ecológico. Foram analisados os casos novos de câncer de tireóide diagnosticados no período de 1997 a 2010 fornecidos pelo Registro de Câncer de Base Populacional de São Paulo e os óbitos por câncer de tireóide ocorridos entre 1981 e 2010 fornecidos pelo Sistema de Mortalidade do Ministério da Saúde (SIM-MS) e pelo Programa de Aprimoramento das Informações de Mortalidade (PRO-AIM). Foram calculados os coeficientes bruto e padronizado de incidência e de mortalidade, foi analisada a tendência destes coeficientes através do modelo de regressão, da mudança percentual anual e do modelo idade-período-coorte. Para a análise espacial foram criados mapas temáticos, calculado o índice de Moran e, para as variáveis com padrão cluster foi calculado o índice local de associação espacial (LISA) e estimados modelos de regressão, tendo como variável dependente os coeficientes e como variáveis independentes os indicadores socioeconômicos (IDH, taxa de alfabetização, coeficiente de Gini e número de moradores por domicílio). Resultados: O coeficiente médio de incidência (1997-2010) foi para o sexo feminino de 17,77 por 100.000 e para o sexo masculino 4,46 por 100.000. Ambos apresentaram tendência crescente. O coeficiente médio de mortalidade (1981-2010) foi para o sexo feminino de 0,50 por 100.000 e para o masculino 0,30 por 100.000, ambos apresentaram tendência decrescente. O tipo histológico papilífero apresentou tendência crescente em ambos os sexos. Para incidência (ambos os sexos) e para mortalidade feminina, os efeitos de idade-período e coorte ofereceram o melhor ajuste; para mortalidade apenas a idade. Na análise espacial incidência apresentou padrão cluster para homens e mulheres. Os modelos finais foram explicados pela índice de desenvolvimento humano e pela média de moradores por domicílio. Conclusão: Na cidade de São Paulo há um aumento da incidência do câncer de tireóide, possivelmente causado pelo diagnóstico precoce e/ou pela exposição a fatores de risco para o desenvolvimento do carcinoma papilífero. Por outro lado, a mortalidade vem decaindo, provavelmente pelo diagnóstico precoce / Introduction: The incidence of thyroid cancer has been increasing worldwide and the reason for this upward remains controversial. The incidence of this cancer is elevated in São Paulo city, however, trend and spatial analysis where never conducted before. Objective: This study aimed to describe incidence (1997-2010) and mortality (1981-2010) rates, to analyze incidence and mortality trends, by gender, by age group, by histologic type (incidence only) and by age-period-cohort effects and to evaluate the spatial distribution. Methods: This is an ecologic study. Incident thyroid cancer cases were selected from Population-Based Cancer Registry of São Paulo city, registered from 1997 to 2010 and data from thyroid cancer deaths were obtained from Ministry of Health Information System on Mortality (SIM-MS) and from Mortality Improvement Program (PRO-AIM), from 1981 to 2010. Crude and age-standardized incidence and mortality rates were calculated, incidence and mortality trends were estimated by regression models, by annual percentage change and by age-period-cohort effects. To analyze the spatial distribution, thematic maps were created, Moran Index was calculated and, for the variables with cluster pattern, Local Spatial Association (LISA) was calculated; regression models were estimated using as dependent variable the rates and as independents variables the socio-economic indicators. Results: The mean incidence rate (1997-2010), for females, was 17.77 per 100,000 and for males was 4.46 per 100,000. Both presented increasing trends during the period. The mean mortality rate (1981-2010) for females was 0.5 per 100.000 and for males was 0.3 per 100.000, both presented decreasing trends. The incidence of papillary cancer increased over the period study for females and males. Age, period and birth cohort effects significantly improved the model fit for incidence (females and males) and mortality (only females); for mortality, only the age effect significantly improved the model fit. There was a clustered spatial pattern for incidence (females and males). The final regression models were significantly fitted by human development index and by average number of inhabitants per household. Conclusion: The incidence of thyroid cancer has increased in São Paulo city, this may be due to increased detection of subclinical disease or/and by exposures to risk factors for development of papillary carcinoma. Otherwise, the mortality rates have decreased, probably because of the detection of subclinical disease

MIRTINGUMO NUO IŠORINIŲ MIRTIES PRIEŽASČIŲ TRENDAI LIETUVOS MIESTO IR KAIMO KOHORTOSE 1967 - 2006 62 puslapiai, 32 grafikai, 2 lentelės. Raktažodžiai: amžiaus - periodo - kohortos analizė, mirtingumas, trendas, savižudybės, autotransporto įvykiai. Tyrimo tikslas: Nustatyti detalius mirtingumo dinamikos nuo savižudybių ir autotransporto įvykių ypatumus 40 - ies metų laikotarpiu priklausomai nuo lyties ir gyvenamosios vietos. Uždaviniai: Apskaičiuoti pagrindinius dinamikos parametrus - amžių, periodą, kohortas ir nustatyti jų įtaką dinamikos procesui; Išanalizuoti du svarbiausius mirtingumo dinamikos faktorius kiekvienai mirties priežasčiai ir sumodeliuoti šių faktorių poveikio kartu įtaką šiam procesui pagal lytį ir gyvenamąją vietą. Nustatyti, kaip paamžiniai mirtingumo rodikliai kinta kiekviename kohortos penkmetiniame intervale, koks šių kreivių lygis įvairiose kohortose ir kaip tai skiriasi pagal lytį ir gyvenamąją vietą. Metodai: Mirčių duomenys nuo savižudybių ir autotransporto įvykių Lietuvoje nuo 1967 iki 2006 m. buvo sugrupuoti į 17 amžiaus grupių ir 8 penkmetinius periodus. Duomenų analizei panaudotas Poissono regresijos metodas pritaikytas amžiaus - periodo - kohortos modelių efektams atskirti. Rezultatai: Ir moterų ir vyrų kaimo populiacijos mirtingumo nuo savižudybių tendencija buvo ryškiai didėjanti per visą analizuojamą periodą. Miesto moterų populiacijoje mirtingumo rodikliai nuo savižudybių mažėjo, išskyrus didėjančius senyvo amžiaus grupių rodiklius. Miesto... [toliau žr. visą tekstą] / MORTALITY TRENDS FROM EXTERNAL CAUSES AMONG URBAN AND RURAL COHORTS IN LITHUANIA 1967 - 2006 62 pages, 32 graphics, 2 tables. Keywords: age – period – cohort analysis, mortality, trends, suicide, vehicle accidents. Research aim: The aim of this study was to examine particular trends of mortality from suicide and vehicle accidents during 40 years period subject to sex and place of residence. The tasks of the research work were as follows: To calculate basic parameters of mortality trends - age, period and cohorts and detect their influence to the process; To analyze two most important factors to variation for each cause of the death and to simulate this along factors' influence to the procces subject to sex and place of residence. To find out how subsequent mortality rates vary in each cohort quinquennial interval, what is the difference of these curves levels in different cohorts and how they differ between sex and place of residence. Methods: Deaths due to suicides and vehicle accidents in the period from 1967 through 2006 and the corresponding population figures were grouped into 17 age groups and 8 5-year periods. These were fitted to Poisson regression models to assess age, period, and cohort effects. Results: Both women's and men's mortality trends from suicides increased dramatically through analyzed period. Trends of urban women's suicide mortality have decreased, except increasing trends of the elderly. Urban men's population had experienced increasing trends from... [to full text]

<p>This dissertation consists of two original empirical studies on the determinants of teenage childbearing in the United States. The first study examines the impact of educational attainment on teenage childbearing, using school entry laws as an instrument for education and a highly detailed North Carolina administrative dataset that links birth certificate data to school administrative records. I show that being born after the school entry cutoff date affects educational success in offsetting ways, with a negative impact on years of education but positive impact on test scores. Using an IV regression strategy to distinguish the impacts of years of education and test scores, I show that both educational measures have negative impacts on teenage childbearing.</p><p>The second study examines potential causes of the decline in the U.S. teenage birth rate between 1991 and 2010. Using age-period-cohort models with Vital Statistics birth data and Census population counts, I show that the decline was driven by period changes in the early 1990s but by cohort changes between the mid-1990s and mid-2000s. I also use a difference-in-differences model to investigate the extent to which social policies in the 1970s-1980s can explain these cohort changes. The evidence suggests that while legalization of abortion for adult women and unilateral divorce laws had a significant impact on teenage birth rates in the 1990s-2000s, abortion legalization is unlikely to be a major explanation for the observed decline.</p> / Dissertation