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This study examines the properties of the linear probability difference-in-differences estimator when the data are in fact generated by a single-decrement, continuous-time hazard process. We focus on the textbook case of two groups and two periods in which the control and treatment groups are observed before and after treatment. We provide formal derivations and illustrate matters concretely by reexamining economic studies that have relied on the linear probability difference-in-differences estimator when attempting to obtain estimates of the causal effect of unilateral and no-fault divorce. In particular, we show that the increasing then decreasing pattern of effects found by Wolfers (2006) can be generated by a time-invariant effect of treatment in a proportional hazard setting. We conclude that often implicit assumptions about how the data are generated are an important and necessary component of causal identification.

This article reports the novel incidental concurrences of multiple oral lesions in a 13-year-old boy. Radiographically, an over-retained primary canine was seen with a subjacent mixed radiopacity and transmigrated permanent canine with a suspected dentigerous cyst (each with gubernacular canals). Treatment consisted of enucleation and removal of the impacted canine. The histopathologic findings were compound odontoma containing multiple tooth-like structures and calcifying odontogenic cyst with epithelium containing ghost cells, calcifications and subjacent fibrous connective tissue wall. All cases of odontomas should undergo microscopic assessment for diagnosis and ascertainment of associated pathosis.

Women in the United States are much more likely to become mothers as teens than those in other rich countries. Teen births are particularly likely to be reported as unintended, leading to debate over whether better information on sex and contraception might lead to reductions in teen births. We contribute to this debate by providing causal evidence at the population level. Our causal identification strategy exploits county-level variation in the timing and receipt of federal funding for more comprehensive sex education and data on age-specific teen birth rates at the county level constructed from birth certificate natality data covering all births in the United States. Our results show that federal funding for more comprehensive sex education reduced county-level teen birth rates by more than 3%. Our findings thus complement the mixed evidence to date from randomized control trials on teen pregnancies and births by providing population-level causal evidence that federal funding for more comprehensive sex education led to reductions in teen births.

Background: In a heavily cited paper, Finer (2007) asserted that by age 30, 82Š of US women born 1939-1948 engaged in premarital sex, increasing to 94Š for those born 1969-1978. Using the same data, our age 30 estimates are 55Š and 87Š for women born 1939-1948 and 1969-1978. Our analyses thus document strikingly different levels and trends. Methods: We replicate Finer's single-decrement Kaplan-Meier estimates of premarital sex using Cycles 3-6 of the National Survey of Family Growth, the same data as analyzed by him. We then contrast such single-decrement estimates for both premarital sex and first marriage with estimates of the simple percentages in three states: an origin state in which women begin life as never-married virgins and two destination states for first sex and for first marriage, depending on which occurs first. These analyses provide an empirical illustration of the fact that single-decrement estimates cannot be interpreted as simple percentages for demographic processes involving multiple decrements. Results: Our cohort estimates document increases in the percent of US women who had premarital sex by age 25, rising from 53Š to 75Š, 83Š, and 87Š for those born 1939-1948, 1949-1958, 1959-1968, and 1969-1978, respectively. Contribution: Our cohort analyses reveal sharp increases in premarital sex for US women born between 1939 and 1968, with increases most rapid for those born in the 1940s and 1950s. Our findings also reemphasize a standard lesson from formal demography - that single-decrement life table estimates cannot be interpreted as simple percentages for a multiple-decrement demographic process.

In this data visualization, the authors document trends in abstaining from sex while never married for U.S. women born 1938–1939 to 1982–1983. Using data from the six most recent National Surveys of Family Growth, the authors’ estimates suggest that for women born in the late 1930s and early 1940s, 48 percent to 58 percent reported abstaining from sex while never married. Abstinence then declined rapidly among women born in the late 1940s through the early 1960s, leveling off at between 9 percent and 12 percent for more recent birth cohorts. Thus, for U.S. women born between the mid-1960s and the early 1980s, roughly one in nine abstained from sex while never married.

Motivated by long-standing debates between abstinence proponents and sceptics, we examine how socio-economic factors influence premarital first births via: (i) age at first sexual intercourse and (ii) the risk of a premarital first birth following the onset of sexual activity. Factors associated with an earlier age at first intercourse will imply more premarital first births owing to increased exposure to risk, but many of these same factors will also be associated with higher risks of a premarital first birth following onset. Our analyses confirm previous findings that women from disadvantaged backgrounds are younger at first intercourse and have higher premarital first-birth risks than women from more advantaged backgrounds. However, differences in onset timing have a strikingly smaller influence on premarital first-birth probabilities than do differences in post-onset risks. Our findings thus suggest that premarital first births result primarily from differences in post-onset risk behaviours as opposed to differences in onset timing.

For demographers, perhaps the most stunning set of changes in the family to have emerged over the last century are changes that drove what appeared to have been exploding populations, both in the world at large as well as in individual countries, to changes that now raise the distinct possibility of future population decline in a non-negligible number of nations. These changes are in turn intimately connected to profound changes in family life and most particularly in fertility—trends in how many women, on average, remain childless over their lifetimes, and for those women who become mothers, how many births they will have. What is especially intriguing is “American exceptionalism”—that the United States appears to have been largely immune, at least to date, from demographic trends that are so pronounced and potentially worrisome in so many other advanced industrialized nations. I review what lies behind the shift from exploding populations to the possibility of population decline in at least some parts of the world, and then speculate on what may be the likely sources of why the United States has been an exception to these trends. This then leads me to highly speculative remarks about why two specific groups very often seen in a negative light—immigrants and women who give birth outside of formal marriage—have played an important role in American demographic exceptionalism, and why these groups may likewise continue to be a major factor in why the future of the United States may be far rosier than that of other advanced industrialized nations. However, I caution that this optimistic scenario depends crucially on realizing the social, economic, and demographic potential of these subpopulations. In this essay, I review what demographers regard as perhaps the most striking family trend to have emerged over the last century—a shift from what appeared to be exploding populations, both in the world at large as well as in individual nations, because too many were having too many children, to the emergence in a growing number of nations of what appears to be a shift in which too many are having too few children. Why might we care about these issues? On one hand, Americans tend to regard the issue of who chooses to remain childless, or how many children are born to those who become parents, as very private matters, to be decided by a pregnant woman or the prospective parents. But we also have a collective interest in children because they constitute the future of any society, and this in turn means that we might worry if too many have too few children. What is especially intriguing is “American exceptionalism,” that the United States appears to be largely immune to what is so pronounced and potentially worrisome in a growing number of nations. So how can it be that worries about an exploding world population have turned into worries about too many having too few children? The correct answer, in my view, is that it remains the case that in some nations, too many are having too many children, with these nations continuing to have far too rapid population growth. There is thus a broad consensus among social scientists that these countries would benefit were rapid population growth to be curbed. But in other nations, there have been emerging trends that look as if too many are having too few children; thus, there has been a growing concern, which I share, that these countries would benefit were these trends to be curbed. In this essay, I review what lies behind the shift from exploding populations to the possibility of population decline. I then discuss what are the likely sources of why the United States has been an exception to trends seen in so many other developed nations of the world. This discussion then leads to highly speculative remarks on my part regarding the future of US, which in my view is likely to be substantially more promising than for most other highly industrialized nations. However, I also note that this optimistic scenario depends crucially on realizing the “demographic potential” of subpopulations that have often been viewed as problematic. This leads me to conclude that these issues will pose difficult but critically important challenges in the coming decades. Keywords: demographic potential; dynamics of population change; fertility change; first demographic transition; immigration; Malthus; nonmarital fertility; population aging; sub-replacement fertility

BACKGROUND In the U.S. today, premarital first births occur disproportionately to women with low education and income. We lack studies of whether this education gradient was present in cohorts born earlier. OBJECTIVE We examine education differences in the proportion of U.S. white and black women who: (a) experienced a premarital conception taken to term resulting in a first birth, and (b) had a premarital first birth by age 35. Among those experiencing a premarital conception, we examine the association between education and whether women married before the birth. We examine these patterns for birth cohorts born between 1925 and 1959. METHODS We use the 1980, 1985, 1990, and 1995 June Fertility Supplements from the U.S. Current Population Survey to examine cohorts of women born between 1925 and 1959. The survey asked women the dates of their first marriage and their first birth, allowing us to determine premarital conceptions taken to term, and whether the resulting first births occurred within or outside of first marriage. We present descriptive information on the proportion of black and white women in each cohort who experienced the events of interest by age 35. RESULTS For all cohorts, women with low education were generally more likely than their more educated counterparts to experience premarital conceptions and premarital first births. For blacks, but not whites, who experienced a premarital conception that was taken to term, those with more education were more likely to marry before the birth. CONCLUSIONS In the U.S., the concentration of premarital conceptions and premarital first births among less educated women was present for cohorts extending back to those born in 1925. 1. Introduction It is well known that, in the U.S., nonmarital births have increased for both whites and blacks (Bachu 1999; Wu 2008; Ventura 2009), and that, in recent decades, women who have nonmarital births are disproportionately of low education and income (Upchurch et al. 2002; Ellwood and Jencks 2004). This paper examines whether the relationship between education and having a premarital conception or first birth existed for earlier U.S. birth cohorts. 2. Data and methods We pool data from the retrospective marital and fertility histories from the June 1980, 1985, 1990, and 1995 U.S. Current Population Surveys (CPS). These June CPS fertility and marital supplements were administered to married women aged 15 or older and never-married women aged 18 or older. We use these data to identify the date (to the nearest month) of first births and first marriages. We assume that all conceptions occurred nine months prior to the birth, and employ a definition of a premaritally conceived but postmarital first birth as a first birth occurring less than seven months after a first marriage.4 This in effect assumes that first births that occur seven or eight months after a first marriage are premature births conceived within marriage. This procedure clearly introduces some classification errors, but provides a standard operational definition of a premarital conception for those conceptions taken to term. Because these data contain no information on pregnancies ending in miscarriage or abortion, our analyses are limited to conceptions taken to term. A further limitation of these data is that they lack information on cohabitation. However, the vast majority of premarital conceptions taken to term and resulting in a first birth to women born between 1925 and 1959 occurred in periods when abortion and cohabitation were relatively uncommon. Unweighted estimates are presented throughout. We limit our analysis to first marriages and first births. For the birth cohorts we examine, about three out of four premarital conceptions taken to term involved first births, and about nine out of ten marriages occurring between a premarital conception and a first birth were first marriages (results not shown). …

This paper outlines decomposition methods for assessing how exposure affects prevalence and cumulative relative risk. Let x denote a vector of exogenous covariates and suppose that a single dimension of time t governs two event processes T1 and T2. If the occurrence of the event T1 determines entry into the risk of the event T2, then subgroup variation in T1 will affect the prevalence T2, even if subgroups in the population are otherwise identical. Although researchers often acknowledge this phenomenon, the literature has not provided procedures to assess the magnitude of an exposure effect of T1 on the prevalence of T2. We derive decompositions that assess how variation in exposure generated by direct and indirect effects of the covariates x affect measures of absolute and relative prevalence of T2. We employ a parametric but highly flexible specification for baseline hazard for the T1 and T2 processes and use the resulting parametric proportional hazard model to illustrate the direct and indirect effects of family structure when T1 is age at first sexual intercourse and T2 is age at a premarital first birth for data on a cohort of non-hispanic white U.S. women.

Previous studies on trends in the intergenerational transmission of divorce have produced mixed findings, with two studies (McLanahan and Bumpass 1988; Teachman 2002) reporting no trend in divorce transmission and one study (Wolfinger 1999) finding that divorce transmission has weakened substantially. Using a stratified Cox proportional hazard model, we analyze data from the National Survey of Families and Households and find no evidence for any trend in divorce transmission. To reconcile apparent differences in results, we note that the General Social Survey data used by Wolfinger lack information on marital duration, permitting analysis only for whether respondents have divorced by interview. As a result, an apparent decline in divorce transmission could be due to inadequate adjustments for the longer exposures to risk by earlier marriage cohorts, yielding a higher probability of divorce by interview for earlier cohorts relative to more recent cohorts even if divorce risks are identical across all marriage cohorts. We confirm this possibility by using a series of discrete-time hazard logistic regressions to investigate the sensitivity of estimates of trends in divorce transmission to different adjustments for exposure to risk. We conclude that there has been no trend in the intergenerational transmission of divorce.

Historical trends in U.S. nonmarital fertility have been compiled almost exclusively from vital statistics on births. This paper complements this historical record by providing cohort estimates of nonmarital fertility for cohorts of U.S. women spanning approximately 50 years of cohort experience. Life table estimates using retrospective marital and fertility histories in the June 1980, 1985, 1990, and 1995 Current Population Surveys reveal nonnegligible levels of nonmarital fertility historically. For women born between 1925 and 1929, nearly 1 in 10 had at least one nonmarital birth by age 30. For women born between 1965 and 1969, more than 1 of 4 had one or more nonmarital births by age 30, with roughly 1 of 5 white, 3 of 5 black, and 1 in 3 Hispanic women having at least one nonmarital birth by age 30. Life table estimates reveal a twofold increase between ages 20 and 30 in the percentage of women with at least one child outside of formal marriage for all cohorts of white and Hispanic women, and an increase of roughly two-thirds for all cohorts of black women. I also document qualitative differences in nonmarital fertility by race/ethnicity, with the percentage of nonmarital births following a divorce or marital separation for white women approximately twice that for black or Hispanic women. Finally, I introduce a new measure, the cohort nonmarital fertility ratio (CNMFR), which provides a cohort complement to the standard period nonmarital fertility ratio. Conservative estimates reveal a roughly threefold increase in the CNMFR for women born from 1925-1929 to 1950-1954 for both whites and blacks, despite substantially higher levels of nonmarital fertility among black women. Overall, these findings reveal surprisingly high levels of nonmarital fertility for women born since the 1920s and confirm that nonmarital fertility has become an increasingly substantial component of overall U.S. fertility

In the 1st-ever use of event-history analysis to investigate discourse processes quantitatively, this study recasts understanding of discourse in terms of the (a) antecedents and (b) consequences of discourse participant "moves" as they (c) affect the inertia of the discourse and accordingly structure unfolding discourse processes. The method is used to compute the probabilities of the effects of particular discourse moves on subsequent discourse patterns and to measure and systematically contrast static (macrosocial) and dynamic (microsocial) conditions prompting and sustaining dialogic discourse. Theoretically, the authors draw on Russian scholar Mikhail Bakhtin's epistemological distinctions between monologic and dialogic discourse to identify pedagogically rich sequences of teacher-student interaction as dialogic spells and discussion, which the authors' previous work has shown to contribute to achievement. Empirically, the authors examine data collected in hundreds of observations of more than 200 8t...

This article provides an overview of current theory and empirical research on the fertility of single or cohabiting parents, with particular emphasis on research in the fields of demography, economics, history, and sociology. Topics covered include: historical shifts in usage concerning the terms employed to refer to these behaviors; measurement issues that arise in the study of nonmarital fertility; demographic trends; functionalist, historical, and policy literatures; empirical research to date on the socioeconomic determinants, including within-country and cross-national variation in the association between nonmarital fertility and socioeconomically disadvantage; consequences for women and children; and the continuing conceptual and theoretical challenges posed by the study of nonmarital fertility.

We examine the effects of family structure on age at first sexual intercourse before marriage for a recent cohort of women. Previous research on the linkage between family structure and sexual initiation has employed relatively crude measures of family structure-typically a snapshot of the respondent's family structure at age 14. We use retrospective parent histories from the 1979-1987 National Longitudinal Survey of Youth to construct dynamic measures of family structure, using information on the number and types of parents in the respondent's household between birth and age 18. We use these measures in proportional hazard models to test the effects of prolonged exposure to a single-mother family, prolonged absence of a biological father, parental presence during adolescence, and family turbulence. For White women, age-specific rates of first sexual intercourse are significantly and positively associated with the number of family transitions; for Black women, age-specific rates are significantly and positively associated with having resided in a mother-only or father-only family during adolescence. Net of other effects of family structure, we find no significant effects for White or Black women of being born out of wedlock, prolonged exposure to a single-mother family, or prolonged absence of a biological father. Our results for White women are consistent with a turbulence hypothesis, whereas for Black women our results suggest the importance of family structure during adolescence. For neither White nor Black women are our results consistent with hypotheses positing earlier initiation of sexual activity for women with prolonged exposure to a single-mother or fatherabsent family. Key Words: family structure dynamics, father abuse, premarital sexual initiation, racial and ethnic differences, single mothers. Numerous studies have found that sexual activity occurs earlier for adolescents who experienced a parental divorce or who have an absent father relative to those who resided with both biological parents (Billy, Brewster, & Grady, 1994; Booth, Brinkerhoff, & White, 1984; Brewster, 1994; Flewelling & Bauman, 1990; Hogan & Kitagawa, 1985; Inazu & Fox, 1980; Newcomer & Udry, 1984; Thornton & Camburn, 1987; Trent & South, 1992; Weinstein & Thornton, 1989; Whitbeck, Simons, & Goldberg, 1996). This empirical association is important because of the increasing prevalence of single-parent families and because early sexual activity may increase the risk of contraceptive nonuse, sexually transmitted disease, teen pregnancy, teen motherhood, and out-of-wedlock childbearing. Despite substantial empirical research, the mechanisms linking family structure to the initiation of sexual activity are not well understood. One difficulty has been the reliance of much previous research on relatively crude measures of family structure-typically a child's family structure at age 14. Such snapshot measures say little about what aspect of family structure influences adolescent behavior, in part because they conflate differences in an adolescent's family trajectory that are, we argue, important in explaining the timing of first intercourse. In addition, snapshot measures ignore the increasingly fluid nature of family life accompanying increases in nonmarital childbearing, divorce, and remarriage. We use data from the National Longitudinal Survey of Youth (NLSY) to examine age-specific rates of first sexual intercourse before first marriage for a nationally representative sample of women who entered adolescence during the late 1970s and early 1980s. We exploit detailed family histories available in the NLSY to estimate the effects of the number of family transitions, exposure to specific types of families, and family structure during adolescence. These results help shed light on how parental socialization, parental supervision during adolescence, and family turbulence may have affected the timing of sexual initiation for this cohort of women. …

Apres un rappel methodologique de l'analyse sequentielle, l'A. expose les forces et les faiblesses de cette technique. Il emet un jugement critique sur les avis de Abbott et Tsay a propos de l'application de l'analyse sequentielle aux carrieres professionnelles. En particulier, l'A. met l'accent sur la question de l'asymetrie des relations unissant les differentes sequences composant une carriere professionnelle. Ce probleme souleve la question des couts en jeu dans les transitions entre les sequences. L'A. defend la methode de l'analyse historique evenementielle et expose en quoi son avis diverge de celui d'Abbott et Tsay

We examine cohort trends in premarital first births for U.S. women born between 1920 and 1964. The rise in premarital first births is often argued to be a consequence of the retreat from marriage, with later ages at first marriage resulting in more years of exposure to the risk of a premarital first birth. However, cohort trends in premarital first births may also reflect trends in premarital sexual activity, premarital conceptions, and how premarital conceptions are resolved. We decompose observed cohort trends in premarital first births into components reflecting cohort trends in (1) the age-specific risk of a premarital conception taken to term; (2) the age-specific risk of first marriages not preceded by such a conception, which will influence women’s years of exposure to the risk of a premarital conception; and (3) whether a premarital conception is resolved by entering a first marriage before the resulting first birth (a “shotgun marriage”). For women born between 1920–1924 and 1945–1949, increases in premarital first births were primarily attributable to increases in premarital conceptions. For women born between 1945–1949 and 1960–1964, increases in premarital first births were primarily attributable to declines in responding to premarital conceptions by marrying before the birth. Trends in premarital first births were affected only modestly by the retreat from marriages not preceded by conceptions—a finding that holds for both whites and blacks. These results cast doubt on hypotheses concerning “marriageable” men and instead suggest that increases in premarital first births resulted initially from increases in premarital sex and then later from decreases in responding to a conception by marrying before a first birth.

This article addresses two questions: First, why is Black unemployment persistently higher than White unemployment? Second, how can this fact be reconciled with narrowing Black/White differentials in educational attainment, occupational position, and earnings? We show that the persistent racial gap in unemployment is due to differential access to employment opportunities by region, occupational placement, labor market segmentation by race, and labor market discrimination. Our findings showing that the racial gap in unemployment is greatest for college-educated men and are consistent with the view that Blacks still encounter barriers to employment in the labor market.

VOLUME 1 Overviews Event History Models for Life Course Analysis - Lawrence Wu Nonparametric Estimation: Theory Nonparametric Estimation from Incomplete Observations - E.L. Kaplan and Paul Meier Theory and Applications of Hazard Plotting for Censored Failure Data - Wayne Nelson Nonparametric Inference for a Family of Counting Processes - Odd Aalen A Flaw in Actuarial Exposed-to-Risk Theory - Jan Hoem Issues in Smoothing Empirical Hazards - Lawrence Wu Nonparametric Estimation: Applications The Incidence of Divorce within Cohorts of American Marriages Contracted since the Civil War - Samuel Preston and John McDonald Slipping Into and Out of Poverty: The Dynamics of Spells - Mary Jo Bane and David Ellwood Trends in Cohabitation and Implications for Children's Family Contexts - Larry Bumpass and Hsien-Hen Lu Cohort Estimates of Nonmarital Fertility - Lawrence Wu The Cox Model: Theory Regression Models and Life Tables - D. R. Cox Understanding Cox's Regression Model: A Martingale Approach - Richard Gill The Cox Model: Applications Unemployment over the Life Cycle: Racial Differences and the Effect of Changing Economic Conditions - Thomas DiPrete Entry into Marriage and Parenthood by Young Men and Women: The Influence of Family Background - Robert Michael and Nancy Brandon Tuma Parametric Models: Theory On the Nature of the Function Expressive of the Law of Human Mortality - Benjamin Gompertz The Distribution by Age of the Frequency of First Marriage - Ansley Coale and Donald McNeil The Process of Entry into First Marriage - Gudmund Hernes A Comparison of the 'Sickle Function' with Alternative Stochastic Models of Divorce Rates - Andreas Diekmann and Peter Mitter VOLUME 2 Parametric Models: Applications The Divergence of Black and White Marriage Patterns - Neil Bennett, David Bloom and Patricia Craig Social Inheritance of Divorce in Postwar Germany - Andreas Diekman and Henriette Engelhardt Legal Environments and Organizational Governance: The Expansion of Due Process in the American Workplace - Lauren Edelman Contextual Effects in the Classroom: The Impact of Ability Groups on Student Attention - Diane Felmlee and Donna Eder The Liability of Newness: Age Dependence in Organizational Death Rates - John Freeman, Glenn Carroll and Michael Hannan Income and Independence Effects on Marital Dissolution: Results from the Seattle and Denver Income-Maintenance Experiments - Michael Hannan, Nancy Brandon Tuma and Lyle Groeneveld Diverging Fertility Among U.S. Women Who Delay Childbearing - Steven Martin Rewards, Resources and the Rate of Mobility: A Nonstationary Multivariate Stochastic Model - Nancy Brandon Tuma Work as a Turning Point in the Life Course of Criminals: A Duration Model of Age, Employment, and Recidivism - Christopher Uggen Time-Varying Covariates: Applications Social Change, the Social Organization of Families and Fertility Limitation - William Axinn and Scott Yabiku Principles of Cohesion in Cohabitation and Marriage - Julie Brines and Kara Joyner An Event History Analysis of Racial Rioting in the 1960s - Daniel Myers Questions in Time: Investigating the Structure and Dynamics of Unfolding Classroom Discourse - Martin Nystrand, Lawrence Wu, Adam Gamoran, Susie Zeiser and Daniel Long Family Structure and the Risk of a Premarital Birth - Lawrence Wu and Brian Martinson Effects of Family Instability, Income and Income Instability on the Risk of a Premarital Birth - Lawrence Wu VOLUME 3 Discrete-Time Models: Theory Discrete-Time Methods for the Analysis of Event Histories - Paul Allison Change and Stability in Educational Stratification - Robert Mare Discrete-Time Models: Applications Mothers, Children, and Cohabitation: The Intergenerational Effects of Attitudes and Behavior - William Axinn and Arland Thornton Two Decades of Family Change: The Shifting Economic Foundations of Marriage - Megan Sweeney No Trend in the Intergenerational Transmission of Divorce - Jui-Chung Allen Li and Lawrence Wu Another Look at the Stratification of Educational Transitions: The Logistic Response Model with Partial Proportionality Constraints - Robert Hauser and Megan Andrew Unobserved Heterogeneity: Theory Heterogeneity's Ruses: Some Surprising Effects of Selection on Population Dynamics - James Vaupel and Anatoli Yashin A Method for Minimizing the Impact of Distributional Assumptions in Econometric Models for Duration Data - James Heckman and Burton Singer Heterogeneity, Omitted Variable Bias and Duration Dependence - Gary Chamberlain Simultaneous Equations for Hazards: Marriage Duration and Fertility Timing - Lee Lillard Kindred Lifetimes: Frailty Models in Population Genetics - J.W. Vaupel Unobserved Heterogeneity: Applications Interrelated Family-Building Behaviors: Cohabitation, Marriage, and Nonmarital Conception - Michael Brien, Lee Lillard and Linda Waite Does Unemployment Cause Future Unemployment? Definitions, Questions, and Answers from a Continuous Time Model of Heterogeneity and State Dependence - James Heckman and George Borjas New Evidence on the Timing and Spacing of Births - James Heckman, V. Joseph Hotz and James Walker VOLUME 4 Competing Risks: Theory A Nonidentifiability Aspect of the Problem of Competing Risks - A Tsiatis The Identifiability of the Competing Risks Model - James Heckman and Bo Honore Competing Risks: Applications Drug Use and Other Determinants of Premarital Pregnancy and Its Outcome: A Dynamic Analysis of Competing Events - Kazuo Yamaguchi and Denise Kandel Social Capital and International Migration: A Test Using Information on Family Networks - Alberto Palloni, Douglas Massey, Miguel Ceballos, Kristin Espinosa and Michael Spittel Nonproportionalmodels Local Hazard Models - Lawrence Wu and Nancy Brandon Tuma Log-Multiplicative Models for Discrete-Time Discrete-Covariate Event History Data - Yu Xie An Approach to Nonparametric Regression for Life History Data using Local Linear Fitting - Gang Li and Hani Doss Trajectories of Fetal Loss in the Czech Republic - Elwood Carlson, Jan Hoem and Jitka Rychtarikova Left Truncation and Left Censoring On the Treatment of Interrupted Spells and Initial Conditions in Event History Analysis - Alfred Hamerle The Distribution of Single Spell Duration Data - Geert Ridder Models for Clustered, Sequential, and Diffusion Processes Estimating a Multivariate Proportional Hazards Model for Clustered Data Using the EM Algorithm, with an Application to Child Survival in Guatemala - Guang Guo and German Rodriguez Multivariate Survivorship Analysis Using Two Cross-Sectional Samples - Mark Hill A Nested Frailty Model for Survival Data, With an Application to the Study of Child Survival in Northeast Brazil - Narayan Sastry Spatial and Temporal Heterogeneity in Diffusion - David Strang and Nancy Brandon Tuma Effects of Exposure on Prevalence and Cumulative Risk: Direct and Indirect Effects in a Recursive Hazard Model - Lawrence Wu and Steven Martin

This paper outlines decomposition methods for assessing how exposure affects prevalence and cumulative relative risk. Let x denote a vector of exogenous covariates and suppose that a single dimension of time t governs two event processes T(1) and T(2). If the occurrence of the event T(1) determines entry into the risk of the event T(2), then subgroup variation in T(1) will affect the prevalence T(2), even if subgroups in the population are otherwise identical. Although researchers often acknowledge this phenomenon, the literature has not provided procedures to assess the magnitude of an exposure effect of T(1) on the prevalence of T(2). We derive decompositions that assess how variation in exposure generated by direct and indirect effects of the covariates x affect measures of absolute and relative prevalence of T(2). We employ a parametric but highly flexible specification for baseline hazard for the T(1) and T(2) processes and use the resulting parametric proportional hazard model to illustrate the direct and indirect effects of family structure when T(1) is age at first sexual intercourse and T(2) is age at a premarital first birth for data on a cohort of nonhispanic white U.S. women.

Most studies that examine the effects of family structure have employed relatively crude measures, typically a snapshot of family intactness at age 14. In this article, we use data from the National Survey of Families and Households to examine (a) how one might better construct measures of family structure that reflect change during early life and (b) what analytical and empirical opportunities are available when the data provide a more complete parent history. We draw four conclusions. First, a substantial fraction of children have extremely diverse parental situations, even though the majority of children live in intact families. Snapshot measures understate greatly the dynamic complexities of a respondent's parental situation. Second, the parent histories of respondents provide a rich but complicated set of longitudinal data and the complexity of these data makes it infeasible to adopt a data-driven approach to summarize family structure over the early lives of children. It is therefore useful to adopt a more theoretical approach in identifying salient dimensions of a respondent's parent history. Third, existing theoretical perspectives conceptualize the influences of parents in markedly different ways. These contrasting views, in turn, imply quite distinct empirical measures. Finally, more informative measures of family structure may allow one to adjudicate between alternative hypotheses of family structure in ways not possible with snapshot measures.

This article assesses the bias and fit of a hazard rate model by comparing predicted and nonparametric estimates of survivor probabilities. These comparisons also generate several diagnostic displays for event history data. We illustrate these diagnostic methods for several global and local hazard models using data on age at first marriage for women from the June 1980 Current Population Survey. Our results suggest that a nonproportional local Gompertz model performs better than other models we examined.

The questions posed by life course researchers often differ in fundamental ways from those posed by sociologists, developmental psychologists, or economists (Elder, 1998; Mayer & Tuma, 1990). For example, life course researchers often focus analytic attention on transitions marking adolescence or early adulthood and the roles and statuses accompanying such transitions (Hogan & Astone, 1986; Modell, Furstenberg, & Hershberg, 1976; Shanahan, 2000). Prototypical questions along these lines include whether certain social groups experience a more rapid transition to adulthood or whether the timing of such transitions (or the duration spent in selected life course statuses) has changed for successive cohorts (Winsborough, 1980). As Mayer and Tuma (1990) note, work in this vein often implicitly conceives of social structure as arising out of individual experiences of varying duration, as opposed to alternative perspectives that see social structure in terms of collectivities of persons with particular fixed attributes (Blau, 1977), as generated from relational networks (and resulting “structural holes”) among individual actors (White, Boorman, & Breiger, 1976) or from the aggregate behavior of rational actors (Becker, 1991).

In a recent paper, Manning, Smock, and Majumdar (2004) examine the stability of marital and cohabiting unions from the perspective of children and find that children born to cohabiting parents are more likely to experience a parental separation than children born to married parents. They find, further, that subsequent marriage among cohabiting parents is associated with increases in the stability of these families, particularly among whites. We rely on the same data, the 1995 National Survey of Family Growth, to extend their findings. We focus on family stability from the perspective of the couple, estimating the risks of union dissolution following a first birth. Our empirical results complement Manning et al.'s by modeling four distinct trajectories of cohabitation and marriage around the time of the first birth and comparing the dissolution risks associated with each. We focus particular attention on comparing the stability of cohabiting couples who marry before a first birth and those who marry after a first birth. For these couples, we find that the ordering of cohabitation, marriage, and childbirth is not associated with union stability, and we interpret this to suggest that many cohabiting couples jointly plan marriage and childbirth.

Ermisch (2009) criticized Gray, Stockard, and Stone (2006), arguing that they incorrectly tested a model positing a nonlinear relationship between the nonmarital fertility ratio and the proportion of unmarried women. I identify a different problem, which is that even if this model were to hold for a particular population, it would not in general hold for subgroups of this population; likewise, were it to hold for subgroups, it would not hold for aggregations of these subgroups.

This paper evaluates the data quality of two demographic variables in light of hypotheses on respondent recall from the literature on survey methodology. An emerging consensus in this literature is that recall of the timing of an event declines with recall duration unless the dating of an event is frequently "rehearsed." We provide empirical evidence consistent with this hypothesis by assessing the quality of demographic data on two event history variables as supplied by female respondents. A first outcome concerns the interval between a first and second birth. We assess examine birth intervals using birth registration data from the Vital Statistics on Natality (VSN) and individual-level survey data from the 1990 June Current Population Survey (CPS), the 1979-93 waves of the National Longitudinal Survey of Youth (NLSY), and the 1988 National Survey of Family Growth (NSFG). Overall, we find relatively little variation in the quality of birth interval data across these four surveys, with onie exception-CPS data in which responses have been allocated. A second demographic variable is age at first sexual intercourse. We engage in several analyses of this variable. First, we use NLSY data to analyze discrepan

In this study I contrast hypotheses about the effects of family structure on premarital birth risks with three income hypotheses: (1) a low income hypothesis--that the risk of a premarital birth is higher for women from disadvantaged economic backgrounds because they possess fewer or less attractive economic opportunities; (2) a permanent income and transitory income hypothesis--that uncertainties generated by unexpected fluctuations in family income increase premarital birth risks net of absolute income levels; and (3) an income level and income change hypothesis--that downward trends in family income reflect worsening socioeconomic opportunities that increase premarital birth risks net of absolute income levels. I use prospective income and retrospective parental histories in the [U.S.] National Longitudinal Survey of Youth to determine if the effect of family instability...is an artifact of low unstable or declining income in the family of origin. (EXCERPT)

The authors examine three hypotheses regarding the impact of a womans family characteristics between birth and age 19 on her chances of having a premarital birth. "We construct dynamic measures of family structure using parent-history data from the [U.S.] National Survey of Families and Households. We use these data to examine the relative importance of family events during childhood changes in family structure during childhood and adolescence and durations spent in the modal family structures experienced by respondents while growing up. Our results suggest that these dynamic measures capture both theoretically and empirically distinct dimensions of family experience and that distinguishing between these dimensions provides sufficient analytical leverage to test the socialization social control and instability and change hypotheses." (EXCERPT)

We introduce a class of local hazard models that maintain parametric assumptions locally rather than globally. These models allow estimation of a flexible baseline hazard rate and nonproportional covariate effects. Recently developed local likelihood methods which generalize maximum likelihood methods can be used to estimate these models. We illustrate these techniques by estimating two local hazard models of first marriage--a local exponential model and a local Gompertz model--from data in the June 1980 [U.S.] Current Population Survey. We also compare results of the local hazard models with those of Coxs model an exponential model a piecewise exponential model and a piecewise Gompertz model. Estimates for the local exponential and local Gompertz models agree closely with nonparametric estimates for various subgroups. Moreover results of the local models provide interesting substantive insights into the process of first marriage that are not easily obtained from global models. (EXCERPT)

This chapter presents a smooth estimator of the hazard rate using a variable-span running loglinear specification that allows investigators to maintain only mild assumptions about the functional forms of population heterogeneity and time inhomogeneity in the rate. This estimator is useful both in exploratory data analyses (EDA) and in checking parametric assumptions. Examples drawn from data on the transition to first marriage for women in the U.S. show that several common parametric assumptions are violated in these data and illustrate that the smoothed hazard estimator can yield important insights not easily obtained from more conventional methods. (EXCERPT)

Roles and ways of thinking about roles have been a major concern of sociologists. One common approach to roles conceptualizes and analyzes them within networks of multiple social relations (see, for example, Radcliffe-Brown, 1940; Barnes, 1954; Nadel, 1957; Mayer, 1966; Kapferer, 1969; Mitchell, 1969; Bott, 1971; Boissevain, 1973; Laumann and Pappi, 1976). A recurrent theme throughout this literature is that the fundamental variables of interest are not particular characteristics of individuals but rather the social relations that connect