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The Total Marital Fertility Rate and Its Extensions

  • Jan M. Hoem
  • Cornelia Mureşan
Article

Abstract

What we will call the age-based TMFR is computed conventionally by adding up age-specific marital fertility rates in the hope of estimating the number of children ever born to a woman who is married throughout her childbearing years. Demographers have long been strongly skeptical about this quantity because it normally indicates implausibly many children. Our analysis of data from the Romanian GGS confirms this finding, and we propose an alternative duration-based TMFR computed in the spirit of parity-progression ratios. At the same time, we extend the method to cover any type of living arrangement (cohabitation, marriage, non-partnered arrangement, and so on). Because each resulting total union-type fertility rate (TUFR) explicitly accounts for the living arrangement, it improves on the conventional total fertility rate (TFR), which does not. We embed the investigation in an event-history analysis with fixed and time-varying control covariates and find patterns of relative risks for such variables that reveal interesting features of childbearing behavior in the Romanian data, which we use to illustrate the method. In most cases, these patterns are quite robust against model re-specification, including the shift from the age-based to the duration-based approach. Since, the number of female respondents is “only” about 6,000 (minus records that cannot be used for the current purpose) in a normal single-round GGS, there is considerable inherent random variation in the data set, but we show that simple few-term moving average graduation suffices to overcome this problem.

Keywords

TFR with marital and co-habitational status Romanian fertility Moving average graduation/curve smoothing 

Le taux de fécondité totale dans le mariage et ses extensions

Résumé

Le taux de fécondité totale en mariage (TFTM) selon l’âge est calculé par convention en sommant les taux de fécondité par âge dans le mariage en vue d’obtenir une estimation du nombre total d’enfants nés d’une femme qui aurait été mariée tout au long de sa vie reproductive. Depuis longtemps les démographes considèrent cette mesure avec scepticisme car elle aboutit souvent à un nombre total d’enfants beaucoup trop élevé. Notre analyse des données du EGG roumain confirme cette constatation et nous proposons dès lors, comme alternative, un TFTM selon la durée, dans l’esprit des probabilités d’agrandissement des familles. Par ailleurs, nous étendons la méthode à tous types de situation de couple (cohabitation, mariage, sans partenaire, etc.). Comme le taux de fécondité totale selon le type d’union (TFTU) tient compte explicitement de la situation de couple, il doit être préféré au TFTM qui ne tient pas compte de ce critère. Notre étude est conduite dans le cadre d’une analyse biographique tenant compte de covariables fixes ou dépendantes du temps. Les résultats de l’analyse nous permettent de découvrir des caractéristiques intéressantes de la fécondité roumaine, que nous utilisons pour illustrer la méthode. Dans la plupart des cas, ces caractéristiques sont robustes face à une re-spécification du modèle, notamment le passage de l’approche basée sur l’âge à l’approche tenant compte de la durée. Comme le nombre de répondants à l’enquête EGG à un passage n’est ‘que’ de l’ordre de 6000 (moins les cas qui n’ont pas pu être utilisés pour le présent travail), il existe une fluctuation aléatoire importante dans les données. Nous montrons toutefois qu’un lissage par moyenne mobile à quelques termes seulement nous permet de surmonter cette difficulté.

Mots-clés

Taux de fécondité totale en mariage et en cohabitation Fécondité roumaine Lissage par moyenne mobile/lissage 

Notes

Acknowledgments

We are grateful to Gerda Neyer for many helpful comments and to Tomas Sobotka for reminding us about the connection of our duration-based features to parity-progression ratios and for providing useful references. The comments by the journal’s editor and referees have been very useful.

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Max Planck Institute for Demographic ResearchRostockGermany
  2. 2.Faculty of Sociology and Social Work, Centre for Population StudiesBabes-Bolyai UniversityCluj-NapocaRomania

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