Tuesday, August 01, 2006

Low Fertility Trap

Low Fertility Trap Follow-up

In his last post Claus has offered us a nice summary of the latest revision of the low fertility trap hypothesis as advanced by Wolfgang Lutz et al. As summarized below, there are three basic components to this hypothesis:



As Lutz says the key idea is that once fertility falls below a certain level (and even in the event that the hypothesis proved to be well founded this level could only be determined empirically, on the basis of actual experience) a self-reinforcing demographic regime may be established from which it is hard to escape, in the sense of raising fertility back up towards replacement levels. The cut-off point which Lutz et al start from is 1.5 (and in this they take their lead from a proposal by Peter Macdonald in this paper ). This figure does seem to have some coherence in terms of actual experience to date, since with the exception of Denmark - which did briefly fall under 1.5 tfr in the 1990s - no country seems to have gone below it and come back up again.
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Economics and Low Fertility, Some Stylised Facts

The Economist has an informative and interesting (if somewhat complacent) article on European fertility this week, and I have a pretty lengthy post on A Fistful of Euros which goes through the main issues raised.
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The Fertility Trap Hypothesis ... Revisited

As the postings, and most notably and impressively the commenting, here at DM are once again ticking along nicely, I thought that I would revisit an oldie but goldie topic, namely the concept of the fertility trap. Waaay back in 2005 :) Edward offered us a very nice summary of the fertility trap hypothesis as it has been conceptualized by the Austrian demographer Wolfgang Lutz. Back then Edward ended his post asking whether new evidence of the hypothesis would be found in the Eurobarometer survey which was due in 2006. Now it seems that we are ready answer that question as Wolfgang Lutz and co-authors inform us in a paper given at this year's PAA 2007. What follows is a cross post from Alpha.Sources of this new contribution together with yet another account of the hypothesis itself;
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Wolfgang Lutz and the Low Fertility Trap

Taking as his starting point the proposition that in the two centuries or so which have lapsed since the ending of the earlier Malthusian demographic regime (which occured more or less similtaneuosly with the arrival of the industrial revolution) no homeostatic demographic equilibrium has been achieved, the demographer Wolfgang Lutz has continued to dig away at the fertility issue to the point that he now feels compelled to ask the question whether or not those societies which may be characterised as experiencing low fertility (below TFR 1.5) may not in fact be caught in some kind of low fertility trap.
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Scrutinizing low fertility

As many European countries are gearing up to reform their pension systems it is really all about the demographics. As life expectancy keeps on rising it is only logical to expect the retirment age to expand with some kind of proportionality. In fact, the real conundrum which is creating much grey hair on the heads of demographers and scientists is really how far life expectancy will and can be pushed? Interesting as this topic is this post will deal with the flip side of the coin which is fertillity and why it is low among many European countries and higher in others?
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Saving Your Bacon

This suggestion by fertility expert Gillian Lockwood has not been getting the coverage it deserves. Lockwood argues that women who are thinking of postponing childbirth should take the precautionary measure of having some eggs frozen. I think this is an excellent, cost effective and very practical suggestion. Basically I would go further than Lockwood and suggest that any women who wants a child eventually but is postponing beyond 25 be encouraged to do this as a precautionary measure at that age. Not because at 25 the issue is pressing, but precisely because it isn't. This means the decision could become a routine one. I think we should have massive public health campaigns about this just as we do with tobacco. That way many women can avoid having the ultimate disappointment later on, and, of course, collectively fertility would almost certainly go up.
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The Low-Fertility Trap

I suppose by-now every right thinking and reasonably well read adult knows what the ’poverty-trap’ is, even if most of us aren’t too clear about what there is to do about it. Being stuck in one of these traps could be thought to be like being stuck in a (not necessarily very deep) well with a slimy surround wall. The more you struggle to get out, the harder it gets: your strength disippates, and the walls get to be even more slippery. This could also be called a negative feedback loop.

Well now there is the suggestion that something similar may exist in the world of fertility. As Wolfgang Lutz suggests in this power point presentation, the critical level may be 1.5. No society which has fallen below this level has -to date - returned above it. (Many thanks here to commenter CapTvK who sent me the link).
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Wolfgang Lutz and the Low Fertility Trap

Back in July I published a post about Austrian demographer Wolfgang Lutz’s hypothesis that those countries which sustain total fertility rates below 1.5 for any length of time may have fallen into a self-reinforcing low-fertility trap. Old Rottenhat (Ray to his friends) argued in comments that I had explained the reasons for the existence of low fertility but that I had not justified the idea that this was a ’trap’. Old Rottenhat was right, and taking advantage of the fact that Lutz himself has now given a fuller outline of the hypothesis at the recent Postponement of Childbearing in Europe Conference (see presentation) I will now try and remedy this lacuna.
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Menarché and Low Fertility

Earlier this morning I read this intriguing paper by US researchers Robert Drago & Amy Varner. The title of the paper is “Fertility and Work in the United States: A Policy Perspective” and it addresses the important issues of gender equality and the historical trend towards declining fertility in the United States. Now while I was thinking of how to write a post on this general topic I wandered over to Brad Delong’s blog and found he had this highly relevant post entitled Menarché vs Monarchy.
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