In my post on Monday I was critical of various aspects of Liam Dann’s Herald pieces in praise of New Zealand’s high rates of immigration. Part of his story was that we simply had to keep on with high rates of immigration or our population would stop growing and……well, there lies dragons, or at very least “economic stagnation” and some existential threat to “New Zealand’s economic and social wellbeing”.

A casual reader might have supposed that there were no examples of countries with flat or falling populations, no straws in the wind we could look at and see how likely it was that a stable or even modestly falling population would represent a serious threat to the living standards (material and otherwise) of New Zealanders.

There was a new wave of Conference Board Total Economy Database data out a couple of weeks ago. It has wider coverage than the OECD databases and the economic estimates are a bit more timely too. I’ve used Conference Board data in numerous posts over the years, with a particular focus on the 40 or so advanced countries (OECD members, EU members, plus Singapore and Taiwan).

Over the last 20 years, 10 of those countries have experienced a fall in the total population, and another two have had almost no population growth.

If one takes a more recent period – just the current decade – all the countries with falling populations are still falling, and they’ve been joined by Portugal. Spain’s population is also now flat.

Of course, the economic performance of one of these countries – Greece – has been truly atrocious. Real GDP per capita is still about 20 per cent below 2007 levels, and even the average level of labour productivity has fallen. But no one supposes that Greece’s economic woes are because the population is flat or falling: if anything plummeting living standards and high unemployment have prompted Greeks to look for better opportunities elsewhere.

Here is the productivity growth (real GDP per hour worked) performance of those countries with flat or falling populations, again over the 20 years to 2018.

A flat or falling population is, of course, no guarantee of economic success (Greece and Portugal are what they are), but it certainly doesn’t seem to have been a major roadblock in the way of strong economic performance over the last 20 years. Even Japan – already rich 20 years ago, and often a poster-child for the alleged economic problems of a falling population – has had productivity growth outstripping that of the median advanced country.

Where would New Zealand fit in that picture? New Zealand – with rapid population growth – managed 24 per cent productivity growth over 20 years, better than Greece and Portugal, but well below the median, let alone the median of the flat/falling population countries.

20 years ago falling populations really were a new phenomenon. And 20 years ago, many of those countries really were rather poor, just a few years out of Soviet domination. Perhaps one needs to look at more recent periods to really see the (alleged) crippling effects of a flat or falling population? So I had a look at the period from 2007 to 2018 (choosing 2007 so as not to start my comparison in the middle of a severe recession), and over that period the median country with a flat or falling population also did materially better than the median advanced country (or the median of the countries with fast population growth). New Zealand, once again, underperformed each of those medians.

But the focus of Liam Dann’s article had been on the population/immigration surge New Zealand has experienced since 2012. I’m very reluctant to put much weight on short-term comparisons (even across a pool of other countries there can be other cyclical factors that muddy the water), but….what the heck, here it is.

You’ll recall my chart showing an estimate of labour productivity growth in New Zealand.

That was basically no productivity growth over the last five years, and perhaps 1 per cent total productivity growth over the period since 2012.

There are various ways of getting an estimate of labour productivity. Mine (in the chart above) averages the two measures of GDP (production and expenditure) and the two hours measures (HLFS and QES). I’m not sure quite what the Conference Board uses, but their numbers aren’t inconsistent (if perhaps a touch lower) than what is in my chart.

Here is productivity growth for the countries with flat and falling populations from 2012 to 2018, with numbers for New Zealand, all advanced countries, and the median of the flat/falling population countries also shown.

Using slightly different estimates, we might have done better than Portugal but that is as far up the ranking as you can get New Zealand over this period, one when we have – on the Dann telling – been blessed by such a beneficient immigration policy (and associated rapid population growth). Of these countries, Japan and Slovakia already have higher average labour productivity than New Zealand does, while many of the countries are now also close. The convergence story in defence of New Zealand (others are just catching up) has long since lost most of its salience: we were supposed to be one of the countries catching up, but we just haven’t been.

For what it is worth, over this particular recent six year window, New Zealand’s productivity growth was not just second lowest on this chart, but second lowest among all the advanced economies.

My main interest is in New Zealand, an incredibly remote set of islands. Over decades now there has been no sign that rapid policy-driven population growth has been helpful to our medium-term economic performance. But there is no necessary reason why issues that might be relevant to our economic underperformance should also be relevant for countries much closer to major markets, supply chains, networks and opportunities.

On the other hand, there is no sign that countries with flat or falling populations are doing particularly poorly. In fact, in economic terms, most seem to have been doing just fine.

Simple cross-country correlations can always only take one so far. After all, the countries with flat or falling populations will include those where people are fleeing underperformance (Greece say) and countries with rising populations will include some of those where people are attracted to economic success (Singapore say): in neither case is it likely that the main direction of causation runs from population growth to economic success.

But, for what they are worth, here is a scatter plot showing population growth and productivity growth across those 40 or so advanced countries over 1998 to 2018 (one dot per country, New Zealand is red).

It isn’t a tight relationship, but it is there (and was there is the economics literature decades ago) and isn’t obviously skewed by a single outlier country. And New Zealand isn’t an outlier either – our productivity growth over 20 years was only a bit less than one might have expected from this crude relationship.

For the much shorter more-recent period (2012 to 2018), the negative relationship is still there but, as one would expect (with other stuff going on), is weaker. But New Zealand more starkly underperforms. Perhaps that underperformance – little or no productivity growth for years – will eventually be revised away. Perhaps.

I’m not one of those with any generalised aversion to population growth. Most population alarmism, at least at the macro level, is misplaced. Technology, ideas etc keep on allowing for rising material living standards for more people. But equally, there is little evidence that rising populations – beyond some critical low thresholds – themselves work to boost material living standards, and some signs that advanced countries with rapid population growth do less well (in material terms) than countries with less rapid population growth (even with all the sometimes conflicting chains of causation at work).

But across advanced countries as a whole even if all that was simply false, we’d still be left with a picture of New Zealand where policy has fuelled rapid population growth for most of the last 70 years, even as our relative economic performance has kept on declining. Whatever the situation in Japan or Slovakia, there is decent prima facie reason to be intensely sceptical of the alleged economic gains to New Zealanders from continued high policy-induced immigration to this extremely remote corner of the world.

And few/no signs that countries with flat or even falling populations need to worry about economic underperformance stemming from such population changes.