Paradigm Shift in Demography? Editorial to the Special Issue “Tempo Effects in Demographic Period Indicators” Marc Luy Demography mainly defi nes itself – in contrast to other disciplines of the social sci- ences – through the indicators resulting from its range of methods, like the “number of children per woman”, “divorces per marriage” or “average life expectancy”. De- rived from the period perspective these indicators are the basis of many studies in the social sciences and also for projecting future trends. Until today, theoretical approaches are rare in demography. Consequently, demography is still a mainly quantitative discipline, however one with important interdisciplinary character since on the one hand all areas of the social sciences are dependent on demo- graphic indicators and on the other hand demography itself uses the theories and hypotheses of its neighbouring disciplines. In recent years, however, the basic and since many decades well established concept of demographic period estimation has been questioned. Shortly before and after the turn of the millennium the demographers John Bongaarts and Griffi th Feeney published two papers in which they showed that age-specifi c period rates – which are the basis of the most commonly used period indicators for fertility (total fertility rate) and mortality (life expectancy) – not only include the relative quantum of the demographic events but also so-called “tempo effects” (Bongaarts/Feeney 1998, 2002). These effects appear whenever the aver- age age at which the analyzed event occurs changes during the period of observa- tion. Since in most applications demographic indicators are supposed to refl ect the currently realized fertility or experienced mortality, according to the authors tempo effects have to be seen as undesired distortions. Therefore, Bongaarts and Feeney suggested to adjust demographic period indicators for tempo effects.1 With this Comparative Population Studies – Zeitschrift für Bevölkerungswissenschaft Vol. 35, 3 (2010): 409-414 (Date of release: 15.09.2011) © Federal Institute for Population Research 2011 URL: www.comparativepopulationstudies.de DOI: 10.4232/10.CPoS-2010-10en URN: urn:nbn:de:bib-cpos-2010-10en8 1 In the German version of this issue we translate the terms “tempo adjustment” and “tempo-ad- justed indicators” by “Tempo-Bereinigung” and “tempobereinigte Indikatoren”. This is contra- dictory to my fi rst German publications on tempo effects where I used the term “tempostand- ardisiert” (Luy 2009a, 2009b, 2011). After discussing this issue with several German speaking colleagues I came to the conclusion that the German term “Bereinigung” fi ts Bongaarts’ and Feeney’s idea better than “Standardisierung”. • Marc Luy410 proposal Bongaarts and Feeney strive for a paradigm shift in demographic analysis. The question is: will this change actually take place? The publications of Bongaarts and Feeney caused an intensive discussion among demographers which resulted in many workshops and special sessions at the most important international conferences. The papers presented at these events and the corresponding publications were dominated by opponents of the tempo approach. However, this should not be surprising and cannot be used as reason for its rejection since such developments are typical for scientifi c innovations and can be observed in several examples in the history of science. Nevertheless, I was also convinced by the arguments of the “tempo opponents” for several years. This changed, however, when I had to prepare a lecture on “special methods in demography” at the Univer- sity of Rostock in 2005, in which I intended to demonstrate the unreasonable con- cept of tempo adjustment to the students. While modelling some examples for rep- resenting the relationships I realized that the tempo approach is not unreasonable at all and that the arguments of the tempo opponents are – according to myself – to some extent based on misunderstandings of Bongaarts’ and Feeney’s approach. Although many methodological issues concerning tempo adjustment are still unsolved and require further intensive research I am by now convinced of the tem- po approach. Consequently, I apply it in my empirical studies whenever possible or I consider at least the possibility that tempo effects infl uence the level of as well as differentials in conventional period indicators. I expect that similar changes in the thinking of the entire demographic community will occur and that tempo-adjusted measures will become established as key or at least additional period indicators in the future. However, tempo-adjusted indicators are still far from being a demo- graphic standard. But there is increasing evidence that the development proceeds in this direction. Especially in fertility research tempo adjustment is spreading in- creasingly. The discussion on the analysis of mortality, however, is still dominated by the tempo opponents, although a rethinking among demographers seems to begin here as well. The dispute among demographers is not irrelevant: it has been shown for the analysis of both fertility and mortality that tempo adjustment can lead to very different conclusions compared to the use of conventional indicators (see e.g. the analysis of fertility conditions in Europe by Goldstein et al. 2009 or of mor- tality differences between Western and Eastern Germany by Luy 2006). Until today the discourse took more or less exclusively place in the English literature. Therefore, I am very grateful to the editors of Comparative Population Studies—Zeitschrift für Bevölkerungswissenschaft for offering me the opportunity to coordinate a special issue on that topic. The bilingual publication of this journal makes it possible to introduce the tempo approach to the German demographic literature. Moreover, the papers of this special issue should also provide very im- portant contributions and new thought-provoking impulses to the international dis- cussion. The fi rst paper “Tempo Effects and their Relevance in Demographic Analysis” by myself provides a general overview of the basic ideas of Bongaarts and Feeney and the previous discussion on the tempo approach (Luy 2010). It is the product of different lectures and several talks which I gave in recent years on this subject. Paradigm Shift in Demography? • 411 The main aim of the paper is to answer typically arising questions such as “what do tempo-adjusted indicators measure?” or “why and for what purpose should I use them?”. Another aim is to dissolve a further confusing aspect of the tempo approach. With regard to tempo effects in fertility and mortality it is often argued that both processes are fundamentally different, and therefore the idea of tempo adjustment could not be simply transferred from one demographic process to the other: every human must die, but some women do not only postpone giving birth, but they do not get any (further) children at all. For the tempo approach, however, it is not of signifi cance when the postponed events occur. Likewise it does not mat- ter whether the considered indicator refl ects demographic quantum (e.g. the total fertility rate) or tempo (e.g. life expectancy). I hope that this article (together with the other papers of this issue) help(s) to clarify such questions and allow(s) more demographers and scholars from related subjects to get a better understanding of the tempo approach. The second paper “Mortality Tempo: A Guide for the Skeptic” by Griffi th Feeney develops a discrete approach to describing and analyzing distortions in indicators for period mortality caused by tempo effects (Feeney 2010). The main aim of this article is to illustrate the idea of Bongaarts and Feeney with regard to the analysis of mortality – which is for many scholars more diffi cult to follow. Christian Wegner’s paper “Tempo Effects in Different Calculation Types of Period Death Rates” builds on the thoughts of Griffi th Feeney and shows that tempo effects emerge in each of the three different variants to calculate age-specifi c death rates as the basis of pe- riod life tables (Wegner 2010). So far, the existence of tempo effects in mortality has been only demonstrated and discussed regarding one way of calculation, and thus this paper provides an important extension of the respective methodological dis- cussion. The main innovation of this paper, however, is the differentiation between two types of tempo effects which have different impacts on the three calculation variants of the death rate. The two last papers deal with tempo effects and demographic indicators re- garding fertility. First, Marc Luy and Olga Pötzsch present estimates of the tempo- adjusted total fertility rate in Western and Eastern Germany from 1955 to 2008 (Luy/ Pötzsch 2010). With this paper the authors fi ll a gap in demographic research on fertility in Germany since a description of trends in the tempo-adjusted TFR did not exist so far. This is a consequence of the fact that the necessary data was not avail- able in offi cial German population statistics until recently. This changed with the supplement of the Population Statistics Act in 2007, making it possible to calculate the tempo-adjusted TFR for Germany with offi cial population data from 2009 on. To estimate the tempo-adjusted TFR for the second half of the 20th and the fi rst years of the 21st century Luy and Pötzsch used several alternative data sources from which the necessary information was derived. In the fi fth paper entitled “Misleading Policy Messages derived from the Period TFR: Should we stop using it?” Tomáš Sobotka and Wolfgang Lutz discuss several politically relevant questions and come to the conclusion that the conventional TFR is inappropriate for practical application since it frequently leads to incorrect interpretations of period fertility levels and trends (Sobotka/Lutz 2010). This can result in distorted policy conclusions and, potentially, • Marc Luy412 in misguided policies. The authors present the tempo-adjusted TFR as a meaningful alternative indicator. Altogether this collection of papers provides a broad overview of the idea, the methodological implementation and the practical implications of Bongaarts’ and Feeney’s tempo approach. Empirical examples help to demonstrate the specifi c as- pects in a comprehensible manner. This is an important extension of the previous discussion of tempo effects which lacks practically relevant questions in large parts. Insiders probably realize that the authors of this special issue are predominantly af- fi liated to the Vienna Institute of Demography of the Austrian Academy of Sciences (VID). This is due to the fact that during the last years, tempo effects became one of the main research topics of the VID, and thus many demographers who work on that subject are associated with this institute. The discussions and seminars held at the VID resulted not only in support, further development and empirical applica- tion of tempo-adjustment but also in alternative methodological approaches (e.g. Ediev 2011). As a consequence it must be admitted that this special issue mainly refl ects the points of view of supporters of the tempo approach. Thus, although all papers went through the standard peer-review process, it cannot be ruled out that they contain some kind of “pro-tempo-bias”. Therefore, however, this collection of papers constitutes a fair counterpart of the previous publications which – as already mentioned – were dominated by tempo-opponents (see e.g. van Imhoff 2001 and Schoen 2004 with regard to fertility and the collection of papers in Barbi et al. 2008 with regard to mortality analysis). For each of the articles in this special issue it is important to keep in mind that tempo adjustment exclusively concerns period indicators and is by no means relat- ed to the estimation of cohort levels and trends. The differentiation between period and cohort perspective is more diffi cult than it might seem at fi rst glance. Mixing up these two perspectives and the wrong assumption that Bongaarts and Feeney introduced tempo adjustment to estimate cohort conditions are the most common sources for misunderstandings and confusions regarding the tempo approach. With the hope that this remark guides readers to understand the basic idea of Bongaarts and Feeney better, I wish everyone interested in developments in demography a stimulating reading. References Barbi, Elisabetta; Bongaarts, John; Vaupel, James W. (Eds.) 2008: How long do we live? Demographic models and refl ections on tempo effects. Demographic Research Mo- nographs 5. Leipzig: Springer. Bongaarts, John; Feeney, Griffi th 1998: On the quantum and tempo of fertility. In: Popula- tion and Development Review 24,2: 271-291 [doi: 10.1111/j.1728-4457.2000.00560.x]. Bongaarts, John; Feeney, Griffi th 2002: How long do we live? In: Population and Devel- opment Review 28,1: 13-29 [doi: 10.1111/j.1728-4457.2002.00013.x]. Ediev, Dalkhat M. 2011: Life expectancy in developed countries is higher than conven- tionally estimated. Implications from improved measurement of human longevity. In: Population Ageing 4,1-2: 5-32 [doi: 10.1007/s12062-011-9040-x]. Paradigm Shift in Demography? • 413 Feeney, Griffi th 2010: Mortality tempo: a guide for the skeptic. In: Comparative Popula- tion Studies – Zeitschrift für Bevölkerungswissenschaft 35,3: 483-496 [doi: 10.4232/10. CPoS-2010-12en]. Goldstein, Joshua R.; Sobotka, Tomáš; Jasilioniene, Aiva 2009: The end of “lowest-low” fertility? In: Population and Development Review 35,4: 663-699 [doi: 10.1111/j.1728- 4457.2009.00304.x]. Luy, Marc 2006: Mortality tempo-adjustment: an empirical application. In: Demographic Research 15,21: 561-590 [doi:10.4054/DemRes.2006.15.21]. Luy, Marc 2009a: Der Einfl uss von Tempo-Effekten auf die ost-west-deutschen Unter- schiede in der Lebenserwartung. In: Cassens, Insa; Luy, Marc; Scholz, Rembrandt D. (Eds.): Die Bevölkerung in Ost- und Westdeutschland. Demografi sche, gesellschaft- liche und wirtschaftliche Entwicklungen seit der Wende. Wiesbaden: VS-Verlag für Sozialwissenschaften: 140-168. Luy, Marc 2009b: Empirische Bestandsaufnahme der Bevölkerungsentwicklung in Ost- und Westdeutschland. In: Schubarth, Wilfried; Speck, Karsten (Eds.): Regionale Ab- wanderung Jugendlicher. Theoretische Analysen, empirische Befunde und politische Gegenstrategien. Weinheim/Munich: Juventa, 43-67. Luy, Marc 2010: Tempo effects and their relevance in demographic analysis. In: Com- parative Population Studies – Zeitschrift für Bevölkerungswissenschaft 35,3: 415-446 [doi: 10.4232/10.CPoS-2010-11en]. Luy, Marc 2011: Demografi e. In: Otto, Hans-Uwe; Thiersch, Hans (Eds.): Handbuch So- ziale Arbeit. Munich: Reinhardt: 221-227. Luy, Marc; Pötzsch, Olga 2010: Estimates of the tempo-adjusted total fertility rate in Western and Eastern Germany, 1955-2008. In: Comparative Population Studies – Zeitschrift für Bevölkerungswissenschaft 35,3: 605-636 [doi: 10.4232/10.CPoS-2010- 14en]. Schoen, Robert 2004: Timing effects and the interpretation of period fertility. In: De- mography 41,4: 801-819 [doi: 10.1353/dem.2004.0036]. Sobotka, Tomáš; Lutz, Wolfgang 2010: Misleading policy messages derived from the period TFR: should we stop using it? In: Comparative Population Studies – Zeitschrift für Bevölkerungswissenschaft 35,3: 637-664 [doi: 10.4232/10.CPoS-2010-15en]. van Imhoff, Evert 2001: On the impossibility of inferring cohort fertility measures from period fertility measures. In: Demographic Research 5,2: 23-64 [doi:10.4054/ DemRes.2001.5.2]: Wegner, Christian 2010: Tempo effects in different calculation types of period death rates. In: Comparative Population Studies – Zeitschrift für Bevölkerungswissenschaft 35,3: 543-568 [doi: 10.4232/10.CPoS-2010-13en]. Dr. Marc Luy ( ). Vienna Institute of Demography of the Austrian Academy of Sciences, Wittgenstein Centre for Demography and Global Human Capital, A-1040 Vienna, Austria. E-Mail: mail@marcluy.eu URL: http://www.marcluy.eu Published by / Herausgegeben von Prof. Dr. Norbert F. Schneider Layout and print: Federal Institute for Population Research, Wiesbaden (Germany) Managing Editor / Redaktion Frank Swiaczny Copy Editor / Schlussredaktion Dr. Evelyn Grünheid Scientifi c Advisory Board / Wissenschaftlicher Beirat Jürgen Dorbritz (Wiesbaden) Paul Gans (Mannheim) Johannes Huinink (Bremen) Marc Luy (Wien) Clara H. Mulder (Groningen) Notburga Ott (Bochum) Peter Preisendörfer (Mainz) Comparative Population Studies – Zeitschrift für Bevölkerungswissenschaft www.comparativepopulationstudies.de ISSN: 1869-8980 (Print) – 1869-8999 (Internet) Board of Reviewers / Gutachterbeirat Martin Abraham (Erlangen) Laura Bernardi (Lausanne) Hansjörg Bucher (Bonn) Claudia Diehl (Göttingen) Andreas Diekmann (Zürich) Gabriele Doblhammer-Reiter (Rostock) Henriette Engelhardt-Wölfl er (Bamberg) E.-Jürgen Flöthmann (Bielefeld) Alexia Fürnkranz-Prskawetz (Wien) Beat Fux (Zürich) Joshua Goldstein (Rostock) Karsten Hank (Mannheim) Sonja Haug (Regensburg) Franz-Josef Kemper (Berlin) Michaela Kreyenfeld (Rostock) Aart C. Liefbroer (Den Haag) Kurt Lüscher (Konstanz) Dimiter Philipov (Wien) Tomáš Sobotka (Wien) Heike Trappe (Rostock) © Federal Institute for Population Research 2011 – All rights reserved